Please help me design my boiler setup

[juddspaintballs]

I'm putting in an outdoor wood boiler to heat my home and garage, as well as domestic water. I'll be using a Heatmor 200css with a domestic coil on it rather than a sidearm or flat plate heat exchanger for the water. I plan to place the unit approximately 100' from my house and about 50' from my single car garage.

1) What size PEX should I use?
1" PEX would be great because I anticipate needing at least 200' of tubing to go from the boiler to the house and back. I'll be self-insulating and water sealing my own lines. Will 1" PEX be enough to heat just my home (drafty 1660 sq ft forced air) or do I need to step up to 1.25" PEX? 100' or so in one direction. It's far easier to find fittings for 1" than it is 1.25". The clamp tool I'm seeing only does up to 1".

2) 3/4" PEX for the domestic coil?
It's separate from the lines dedicated to heating the home. Cold well water to the furnace coil, hot domestic water back to the house. Is 3/4" going to be plenty for just that? 100' or so in one direction as well.

3) Garage heat PEX size?
Only 50' away from the boiler. Totally uninsulated small garage, single car sized. I'm going to put a water/air exchanger with a fan behind it hanging from the ceiling. I'm not looking to keep the place 75 degrees, but 50-60 degrees would be nice. I was thinking maybe 3/4" PEX again?

4) Splitting the lines?
The house and garage aren't very close to each other. Would it make the most sense to Tee the output directly at the furnace so one side goes to the house for heat and the other goes to the garage for heat? Then, bring the two loops back together with a Tee right at the inlet side of the furnace again? Control valves on everything. Separate pumps for each loop? The domestic coil is totally separate and pumped via my well pump/house water pressure.

5) Manifold?
Right now all I have in the house is a forced air setup. All I need is a water/air heat exchanger in my plenum as far as I know. My tile kitchen floor is ventless, however, and my feet are quite cold. It would be quite difficult to add a vent to the kitchen near the floor, and equally difficult to add radiant heat by design of the house. I am thinking about adding baseboard heat along the bottom of the cabinets from the hot water. Should I build a small manifold in the house to split the water/air exchanger and the baseboard in the kitchen or could I just incorporate the loop back to the boiler into the baseboard heat? I don't need to make it a separate zone, just warm up the kitchen a little.

6) Sharkbite or stainless steel clamps?
Sharkbites look really simple to use and are cheaper than buying the clamp tool. The clamps shouldn't fail over time because they don't have any o-rings. Which would you recommend? I plan on purchasing as much as possible from pexsupply.com

 

[pybyr]

Right now all I have in the house is a forced air setup. All I need is a water/air heat exchanger in my plenum as far as I know. My tile kitchen floor is ventless, however, and my feet are quite cold. It would be quite difficult to add a vent to the kitchen near the floor, and equally difficult to add radiant heat by design of the house. I am thinking about adding baseboard heat along the bottom of the cabinets from the hot water. Should I build a small manifold in the house to split the water/air exchanger and the baseboard in the kitchen or could I just incorporate the loop back to the boiler into the baseboard heat? I don't need to make it a separate zone, just warm up the kitchen a little.

Got any floor or wall space in the kitchen to put in an old fashioned cast-iron radiator, or a wall-hung panel radiator? Or a room-specific coil/ heat exchanger with blower? Some possible ideas here:

http://www.houseneeds.com/shop/atop/heatersbaseboardradiantindex.asp

Also, you may be able to "balance your ducts" to send more air flow to the kitchen (you use in-duct dampers to restrict flow to other areas so that more air/ warmth flows to the kitchen); or an inline duct-booster fan (google it).

 

[juddspaintballs]

Duct balancing really wouldn't help a whole lot in my kitchen based on the position of the only vent, tucked away behind a corner. It's an old cutup house that has some challenging issues as far as running ductwork, and my kitchen just missed out on having adequate heat. An old style cast-iron radiator could potentially work and it would actually be quite fitting in my 135 year old home, but wouldn't it be just as easy to run a single baseboard style radiator along the bottom of my cabinets and not have anything taking up space in my kitchen? I don't think the price difference would be much at all.

 

[webie]

I am not sure that you would really want radiator heating along the base of your cabinets , first I dont think that it would fit height wise as my base board heaters looks about 8 inches tall and my kick space is about 4 . Another reason I wouldnt but this is toatally up to you is kick space is just that its a space for your toes or room so you don't kick your cabinets and such by useing this space for radiators you will be kicking them . My kitchen has no room for heaters either what I have is , http://www.houseneeds.com/shop/myson/mysontoekickspacebuy.asp Just like this under my kitchen sink .
There is a three speed fan control or off position , I am thinking you could probably some how plumb this inline as when your Hx calls for heat some water would be directed to this .
This is a great toe warmer as it blows on your toes when you are by the kitchen sink.
Webie

 

[juddspaintballs]

that would be perfect, though I'm starting to like the idea of an old cast iron radiator fixing the kitchen heat isn't as much of a concern as actually getting the system up and running to start with. that can always be added at a later date.

 

[joecool85]

You're going to want 1 1/4" to heat your home. 1" can't carry more than 80,000 btu and you'll want more than that.

 

[juddspaintballs]

so...what about connections? I haven't found a crimp tool that will do 1 1/4".

 

[juddspaintballs]

For that matter, I can't find any o2 barrier PEX or any fittings in the 1 1/4" range. Help?

 

[shawntitan]

The numbers might not be right, but I heat 3600 sq ft in NJ with a coil in my duct work, through 1" pex, and it has no problem keeping up with my demand.... I priced out larger sized pex and the price difference was shocking.

 

[Frozen Canuck]

I'm putting in an outdoor wood boiler to heat my home and garage, as well as domestic water. I'll be using a Heatmor 200css with a domestic coil on it rather than a sidearm or flat plate heat exchanger for the water. I plan to place the unit approximately 100' from my house and about 50' from my single car garage.



1) What size PEX should I use?
1" PEX would be great because I anticipate needing at least 200' of tubing to go from the boiler to the house and back. I'll be self-insulating and water sealing my own lines. Will 1" PEX be enough to heat just my home (drafty 1660 sq ft forced air) or do I need to step up to 1.25" PEX? 100' or so in one direction. It's far easier to find fittings for 1" than it is 1.25". The clamp tool I'm seeing only does up to 1".


FWIW I ran into the same prob with my install, wound up going with dual 1" supply to house as 1.25" was special order locally as well as fittings, tools etc. Dual 1" should cover your home but do a heatloss calc to be sure before spending all that $$$$. Make sure on the length of run as you do not want any joints in the pipe underground. You mention drafty, you will need to deal with that as well as maybe add more insulation when you can, otherwise your heating the great outdoors & it will take all the btu's you care to send.



2) 3/4" PEX for the domestic coil?
It's separate from the lines dedicated to heating the home. Cold well water to the furnace coil, hot domestic water back to the house. Is 3/4" going to be plenty for just that? 100' or so in one direction as well.


Not necessary, you can run 1 supply to dhw HX first, then to other house load. Those internal coils are generally throw away units. With a HX in the home you can clean it annually or whenever required (depends on your water quality).



3) Garage heat PEX size?
Only 50' away from the boiler. Totally uninsulated small garage, single car sized. I'm going to put a water/air exchanger with a fan behind it hanging from the ceiling. I'm not looking to keep the place 75 degrees, but 50-60 degrees would be nice. I was thinking maybe 3/4" PEX again?


First off insulate, as heating an uninsulated building is going to create some serious condensation issues on the interior of the walls, as that will be where hot meets cold. Not sure if 0.75"will cover the load in the building, you may need 1". Do a heat loss calc here too.



4) Splitting the lines?
The house and garage aren't very close to each other. Would it make the most sense to Tee the output directly at the furnace so one side goes to the house for heat and the other goes to the garage for heat? Then, bring the two loops back together with a Tee right at the inlet side of the furnace again? Control valves on everything. Separate pumps for each loop? The domestic coil is totally separate and pumped via my well pump/house water pressure.


Suggest you use a simple distribution manifolds on the rear of the unit, as space is very limited on an OWB. Place pumps inside where you can access for service, inspection, replacement & not worry about the time of day or the weather. Think about changing a pump in the dark outside in a storm & you realize why this is a good idea. As to the T's if they are underground then no. All underground pipe should run from access point A to access point B with no joints.



5) Manifold?
Right now all I have in the house is a forced air setup. All I need is a water/air heat exchanger in my plenum as far as I know. My tile kitchen floor is ventless, however, and my feet are quite cold. It would be quite difficult to add a vent to the kitchen near the floor, and equally difficult to add radiant heat by design of the house. I am thinking about adding baseboard heat along the bottom of the cabinets from the hot water. Should I build a small manifold in the house to split the water/air exchanger and the baseboard in the kitchen or could I just incorporate the loop back to the boiler into the baseboard heat? I don't need to make it a separate zone, just warm up the kitchen a little.


Suggest that you oversize your water to air HX you wont regret too big but you sure will regret too small. Yes another heat loss calc necessary. The only way I see for the tile to be warm in the present state (without a reno) of the home is with radiant, sounds like every other option gets in the way.



6) Sharkbite or stainless steel clamps?
Sharkbites look really simple to use and are cheaper than buying the clamp tool. The clamps shouldn't fail over time because they don't have any o-rings. Which would you recommend? I plan on purchasing as much as possible from pexsupply.com

This is prob the smallest $$$$ you will spend therefore I suggest you use fittings that are recommended by the manufacturer of your pipe, no point voiding a warranty. Approved fittings will also make your ins co & inspector easier to get along with. No point tossing all that out the window for a few $$$$. Hope this helps.

 

[Frozen Canuck]

Sorry something went wrong with osting that response. Prob operator error :bug:

 

[Gooserider]

I'm putting in an outdoor wood boiler to heat my home and garage, as well as domestic water. I'll be using a Heatmor 200css with a domestic coil on it rather than a sidearm or flat plate heat exchanger for the water. I plan to place the unit approximately 100' from my house and about 50' from my single car garage.

I'd love to urge you to do a gasifier - for all the reasons listed all over the forums, but... Also doing the domestic coil in the boiler is a really bad idea, waste of money for something that probably won't work well...

1) What size PEX should I use?
1" PEX would be great because I anticipate needing at least 200' of tubing to go from the boiler to the house and back. I'll be self-insulating and water sealing my own lines. Will 1" PEX be enough to heat just my home (drafty 1660 sq ft forced air) or do I need to step up to 1.25" PEX? 100' or so in one direction. It's far easier to find fittings for 1" than it is 1.25". The clamp tool I'm seeing only does up to 1".

As mentioned, you need to do heat calcs all over, but 1" almost certainly won't do it, especially not without a really oversized power-hungry pipe. I would go with either dual 1" lines or 1.25" - the 1.25" is harder to find, but it is out there. At least one user has said they've done 1.25" using brass barbed hose fittings and stainless wormdrive clamps, so there are options in that regard.

I would NOT do "thermapex" or any of the other pre-insulated lines - going from posts here, the experience with them has been mixed in terms of how well they work. It appears you are much better off doing the closed cell spray foam in the trench approach - lower cost per foot, and better performance. Note that except for maybe the boiler, the lines will be your biggest single expense, and if you don't get them right, they will cause you no end of headaches, while being the hardest and most expensive item to fix.

2) 3/4" PEX for the domestic coil?
It's separate from the lines dedicated to heating the home. Cold well water to the furnace coil, hot domestic water back to the house. Is 3/4" going to be plenty for just that? 100' or so in one direction as well.

This is a REALLY BAD idea... You will be paying for an extra run of PEX, and will probably not get acceptable performance, as even the best insulated line will cool when water sits in it - and you will then have to run the water for how long to get the hot water the 100+ from the boiler to your faucet? Even if well water is "free" how many times a day will you be needing to do this, and what kind of strain will it put on your well, and on the other side, your septic system? (If you're on a well, I doubt you'd have town sewer...) Much better to put a sidearm or flat plate in the house with a storage tank (And that approach will probably cost less than what the PEX run would have)

3) Garage heat PEX size?
Only 50' away from the boiler. Totally uninsulated small garage, single car sized. I'm going to put a water/air exchanger with a fan behind it hanging from the ceiling. I'm not looking to keep the place 75 degrees, but 50-60 degrees would be nice. I was thinking maybe 3/4" PEX again?

Again, heat load calcs, and as mentioned you really need to insulate. Doing so will reduce your total heat load, which in turn reduces the size of PEX needed, and all the rest of the various components like pumps and so forth. Incidentally the same thing applies to the house as well - draft sealing and insulation improvements will do FAR more for your heat than anything you can do in the way of equipment... Also keep in mind that that HX will be very exposed to cold air, and will likely be at high risk for freezing, especially in an uninsulated structure. Insulation won't cure all problems that way, but it will help...

4) Splitting the lines?
The house and garage aren't very close to each other. Would it make the most sense to Tee the output directly at the furnace so one side goes to the house for heat and the other goes to the garage for heat? Then, bring the two loops back together with a Tee right at the inlet side of the furnace again? Control valves on everything. Separate pumps for each loop? The domestic coil is totally separate and pumped via my well pump/house water pressure.

Definitely at one end or the other, and not in the middle. From your description, sounds like doing it off the back of the boiler is the best approach. Keep all the plumbing except for the PEX itself above ground, or at least readily accessible.

5) Manifold?
Right now all I have in the house is a forced air setup. All I need is a water/air heat exchanger in my plenum as far as I know. My tile kitchen floor is ventless, however, and my feet are quite cold. It would be quite difficult to add a vent to the kitchen near the floor, and equally difficult to add radiant heat by design of the house. I am thinking about adding baseboard heat along the bottom of the cabinets from the hot water. Should I build a small manifold in the house to split the water/air exchanger and the baseboard in the kitchen or could I just incorporate the loop back to the boiler into the baseboard heat? I don't need to make it a separate zone, just warm up the kitchen a little.

I would at least put a couple tees in the line and design so that whatever you decide to do is reasonably easy to add onto w/o having to rip the existing stuff apart. As mentioned, oversize the W/A HX for your forced air system, the lower the water temp you can run the system at, the better it will work for you.

6) Sharkbite or stainless steel clamps?
Sharkbites look really simple to use and are cheaper than buying the clamp tool. The clamps shouldn't fail over time because they don't have any o-rings. Which would you recommend? I plan on purchasing as much as possible from pexsupply.com

Some folks like sharkbites, but they get REALLY expensive fast - and IMHO they aren't as reliable as the clamps. I'd say do it right and get the clamp tool setup or whatever is recommended for the PEX you'll be using.

Gooserider

 

[WoodNotOil]

juddspaintballs

Many states are strictly regulating these. You will want to make sure you are in compliance and install it correctly so that you don't have hassles down the road.

My father has operated a Heatmor for 7 or 8 years now and while it does heat his house well, it burns vast amounts of wood. I own a Tarm gasser and burn 1/4 to 1/3 of the amount of wood he does per year. If I were you I would go for a gasification boiler and put it inside, in an attached structure, or in a shed in order to not have problems in the future with state regulations.

 

[juddspaintballs]

I'd love to urge you to do a gasifier - for all the reasons listed all over the forums, but... Also doing the domestic coil in the boiler is a really bad idea, waste of money for something that probably won't work well...

Not going with a gassifier. Already have a 200CSS. The domestic coil has been working very well for my parents and they have their water heater shut off and bypassed.

As mentioned, you need to do heat calcs all over, but 1" almost certainly won't do it, especially not without a really oversized power-hungry pipe. I would go with either dual 1" lines or 1.25" - the 1.25" is harder to find, but it is out there. At least one user has said they've done 1.25" using brass barbed hose fittings and stainless wormdrive clamps, so there are options in that regard.

I would NOT do "thermapex" or any of the other pre-insulated lines - going from posts here, the experience with them has been mixed in terms of how well they work. It appears you are much better off doing the closed cell spray foam in the trench approach - lower cost per foot, and better performance. Note that except for maybe the boiler, the lines will be your biggest single expense, and if you don't get them right, they will cause you no end of headaches, while being the hardest and most expensive item to fix.

1 1/4" is it then. Barb fittings and wormdrive clamps. Fine by me. I plan on insulating myself, not buying pre-made pipe. I haven't figured out what kind of insulation I'm going to use, but it will be better than the pre-made stuff.

2) 3/4" PEX for the domestic coil?
It's separate from the lines dedicated to heating the home. Cold well water to the furnace coil, hot domestic water back to the house. Is 3/4" going to be plenty for just that? 100' or so in one direction as well.

This is a REALLY BAD idea... You will be paying for an extra run of PEX, and will probably not get acceptable performance, as even the best insulated line will cool when water sits in it - and you will then have to run the water for how long to get the hot water the 100+ from the boiler to your faucet? Even if well water is "free" how many times a day will you be needing to do this, and what kind of strain will it put on your well, and on the other side, your septic system? (If you're on a well, I doubt you'd have town sewer...) Much better to put a sidearm or flat plate in the house with a storage tank (And that approach will probably cost less than what the PEX run would have)

I'm going to do the domestic coil. I'm thinking of using the 3/4" hot water line insulated together with the intake line for the heat because 1) they should be the same temperature and 2) the heat line should help keep the hot water line warm. No problems with cold water at my parents' house using the same furnace/domestic coil so I don't anticipate any problems here either.

Garage heat PEX size?

Again, heat load calcs, and as mentioned you really need to insulate. Doing so will reduce your total heat load, which in turn reduces the size of PEX needed, and all the rest of the various components like pumps and so forth. Incidentally the same thing applies to the house as well - draft sealing and insulation improvements will do FAR more for your heat than anything you can do in the way of equipment... Also keep in mind that that HX will be very exposed to cold air, and will likely be at high risk for freezing, especially in an uninsulated structure. Insulation won't cure all problems that way, but it will help...

That garage isn't worth insulating. It should be replaced in a few years. I was thinking of totally isolating and draining the lines when I'm not working in the garage so it's not always going to be running. The original install I do probably won't even have the garage heat setup, just prepared for when I'm ready.

Splitting the lines?
The house and garage aren't very close to each other.

Definitely at one end or the other, and not in the middle. From your description, sounds like doing it off the back of the boiler is the best approach. Keep all the plumbing except for the PEX itself above ground, or at least readily accessible.

I haven't decided whether to split the line at the furnace or in the house yet, but right now I'm leaning toward splitting inside the house via a manifold for future expansion.

Manifold?

I would at least put a couple tees in the line and design so that whatever you decide to do is reasonably easy to add onto w/o having to rip the existing stuff apart. As mentioned, oversize the W/A HX for your forced air system, the lower the water temp you can run the system at, the better it will work for you.

Sounds good

Some folks like sharkbites, but they get REALLY expensive fast - and IMHO they aren't as reliable as the clamps. I'd say do it right and get the clamp tool setup or whatever is recommended for the PEX you'll be using.

You've convinced me to use barbs and wormdrive clamps. Thanks for your help Gooserider.


----------------------

juddspaintballs

Many states are strictly regulating these. You will want to make sure you are in compliance and install it correctly so that you don’t have hassles down the road.

I bought the furnace before the regulations went into effect. Worst case scenario: Anthracite is cheap and the regulation only mentions outside WOOD boilers. Thank you for your concern though. I don't have any neighbors to complain.

 

[Tennman]

We had to use 1 1/4 for our application just to get the btus/hr. I had to buy two rolls and can't remember how long each roll was. I shopped and ordered from a local plumbing supplier. They let me borrow the PEX tool that stretches the ID of the PEX to install the fittings. I had never done PEX fittings before but was amazed how easy it was. I was very impressed with the process. 1.25 fittings aren't cheap, but it was important to me to do these fittings right. Since these joints are above ground I guess if the barbed fittings didn't work you could replace with the PEX fittings later. How you do the insulation is critical and you'll probably do your own insulation because the pre-insluated 1.25 stuff is about $14/ft. Read here how to insulate and if you want PM me to learn what not to do. I'm redoing mine in about a month.

 

[Gooserider]

Some folks like sharkbites, but they get REALLY expensive fast - and IMHO they aren’t as reliable as the clamps. I’d say do it right and get the clamp tool setup or whatever is recommended for the PEX you’ll be using.

You’ve convinced me to use barbs and wormdrive clamps. Thanks for your help Gooserider.

Note, I was ONLY talking about doing the barbs and wormdrive clamps on the 1.25" PEX if you can't figure a way to do regular PEX fittings on that size. Anything in the sizes you can use the proper stainless PEX clamps or one of the other proper PEX termination methods, that is what I would do... If you start getting very many of the Sharkbites, the cost will quickly add up to more than the cost of the tooling for the SS PEX clamps, and once you have the tooling, the cost per connection goes way down, while Sharkbites take a big chunk out of your wallet with every joint...

I would NOT do hose barbs and worm clamps on 1" or smaller PEX.

Gooserider

 

[juddspaintballs]

Alright. Here's my plan as of right now:

Buy 2 100' rolls of 1.25" hePEX plus for about $290/ea from pexsupply.com. I've found a better location for the OWB that sits about 75' from the house, so 100' in one direction is perfect for that. Terminate the 1.25" into a self-made manifold in the basement. Then, I'll also buy a few feet of 1" PEX to run ~10' from the manifold to the water/air heat exchanger.

After that, I'd like to use 3/4" for future garage heat and expanding a little heat toward my kitchen floor too. I can't seem to find O2 barrier 3/4" PEX. Is that important?

And of course, I need 3/4" for the domestic coil that I so stubbornly want to use. That doesn't need to be O2 barrier as far as I know since it terminates open at a faucet. Is that correct?

Of course, valves everywhere important for shutting down sections and such. Where should I put pump(s)? One at the OWB to circulate the 1.25" loop, and then one on each loop coming off of the manifold?

And speaking of manifolds, if I brought the 1.25" PEX in and expanded it to 1.5" black iron pipe with 1" reducing T's for as many connections as I wanted, would that be OK? I know very little about designing a manifold. Any links and information in this area would be great.

 

[Gooserider]

Alright. Here's my plan as of right now:

Buy 2 100' rolls of 1.25" hePEX plus for about $290/ea from pexsupply.com. I've found a better location for the OWB that sits about 75' from the house, so 100' in one direction is perfect for that. Terminate the 1.25" into a self-made manifold in the basement. Then, I'll also buy a few feet of 1" PEX to run ~10' from the manifold to the water/air heat exchanger.

Sounds reasonable

After that, I'd like to use 3/4" for future garage heat and expanding a little heat toward my kitchen floor too. I can't seem to find O2 barrier 3/4" PEX. Is that important?

You mean like this.... http://www.pexsupply.com/ThermaPEX-LK-PEX-T075-300-3-4-ThermaPEX-Oxygen-Barrier-PEX-Tubing-300-ft-coil-3721000-p :coolgrin: O2 barrier is not critical if you are running an open system like the OWB you are planning, but if / when you decide to upgrade to a pressurized system, the O2 barrier is VITAL... I would not even think of putting in non-O2 barrier for a heating system.

And of course, I need 3/4" for the domestic coil that I so stubbornly want to use. That doesn't need to be O2 barrier as far as I know since it terminates open at a faucet. Is that correct?

I still think it's a bad idea, but if you insist on doing it, you are correct, it doesn't need to be O2 barrier. (Indeed, you may need to be careful, as my understanding is that at least some of the O2 barrier may not have all the markings on it that code requires for a potable water line.)

Of course, valves everywhere important for shutting down sections and such. Where should I put pump(s)? One at the OWB to circulate the 1.25" loop, and then one on each loop coming off of the manifold?

Depending on how you design the manifolds, you could do the zoning with either pumps or zone valves. If you want to do pumps, set up the OWB lines as a primary/secondary loop w/ close spaced tees, and pull the zone feeds off with pumps. If doing zone valves, make separate supply and return manifolds, and go from there - note that if you do the ZV approach, you will probably want to use a temp or pressure controlled variable speed pump, or put a pressure bypass valve between the two manifolds. Given what you are describing for a system, I'd probably go with the P/S approach.

Another thing I would put in the trench along with the water lines, and your AC power supply is a one or two empty runs of 3/4" PVC conduit, or equivalent, (keep them on the other side of the trench from the power line) to give you the option of running low voltage monitoring and control lines to the boiler - note that AC and low voltage lines can NEVER occupy the same conduit... While you can run a P/S pump setup all the time, it will save you a fair bit of juice to set up a way to turn the boiler pump off if none of the zones are calling for heat - putting in some control lines will make that a lot easier to do.

And speaking of manifolds, if I brought the 1.25" PEX in and expanded it to 1.5" black iron pipe with 1" reducing T's for as many connections as I wanted, would that be OK? I know very little about designing a manifold. Any links and information in this area would be great.

That would be an excellent approach - never hurts to go up in size (within reason) on the manifold, while reducing size can be a bad thing...

Gooserider

 

[juddspaintballs]

Ooooh, primary and secondary manifolds and zone valves. Excellent advice! That makes a whole lot more sense. I'll do a little research on zone valves tonight since I know very little about them.

As far as pumps - you suggested a variable speed pump. I can get on board with that. What would be a decent pump for my described setup? Should I put the pump at the OWB on the supply line or in the basement maybe a foot or two prior to the primary manifold? The OWB is going to be slightly uphill of the house and obviously up in elevation from the basement.

Extra runs of 3/4" electrical conduit. Will do. Thanks for the tips.

I'll make my manifolds as described then. I figured that way, I could easily expand and add more zones if necessary without totally rebuilding the manifold. Just remove the endcap and add another nipple and T and I have a new zone (or a place to put a thermometer or pressure gauge).

 

[heaterman]

1" for the house is right at the ragged edge of capacity. I'm guessing worst case that you would need 50 btu/sq ft and that would put you at 80,000 which is about tje limit for 1". We have used the domestic coil approach in more than a few installs and have had good results with it. We simply tee it into the cold water line going into the present water heater like one would set up a bypass loop. The incoming water goes out to the coil first, picks up whatever heat it can and comes back preheated so the large percentage of the load on the water heater is eliminated. Summer time you just close the bypass and let the water heater function as normal. You'll definitely want 1" to that little garage. If it's uninsulated it may take as much heat as the house so flow rates will be the same.

 

[joecool85]

1" for the house is right at the ragged edge of capacity. I'm guessing worst case that you would need 50 btu/sq ft and that would put you at 80,000 which is about tje limit for 1". We have used the domestic coil approach in more than a few installs and have had good results with it. We simply tee it into the cold water line going into the present water heater like one would set up a bypass loop. The incoming water goes out to the coil first, picks up whatever heat it can and comes back preheated so the large percentage of the load on the water heater is eliminated. Summer time you just close the bypass and let the water heater function as normal. You'll definitely want 1" to that little garage. If it's uninsulated it may take as much heat as the house so flow rates will be the same.

Depends on how warm he needs his garage. I will work in a garage at 45-50F no problem all day myself. 3/4" would give a max of 40k btu and I can't imagine that wouldn't get him into that temp range most if not all days of the year.

 

[juddspaintballs]

I might as well just do 1" to the garage. I need a little bit of 1" to go from the manifold to the water/air heat exchanger in my plenum. If I just buy a larger roll of 1" PEX, I'll run that to the garage and (hold your breath)....

ditch the domestic coil idea! If I do that, I won't need any 3/4" PEX. The domestic coil is $195, I've found a 30 plate exchanger for $199 (I haven't shopped around a whole lot) and from what I hear a 30 plate should give me all the hot water I'll ever need just like a domestic coil, but at the advantage of not needing an extra 100' of 3/4" PEX. Do you think I'd be able to shut off my water heater if I used a 30 plate exchanger? Also, how would I control that as far as zoning as in would I run it off of the same line as the air/water exchanger or would I put it on it's own zone and constantly keep water circulating through at the slowest speed on the variable speed pump?


I still have no idea on which pump and where to place it. Can anyone give me insight on that?

 

[Gooserider]

Ooooh, primary and secondary manifolds and zone valves. Excellent advice! That makes a whole lot more sense. I'll do a little research on zone valves tonight since I know very little about them.

As far as pumps - you suggested a variable speed pump. I can get on board with that. What would be a decent pump for my described setup? Should I put the pump at the OWB on the supply line or in the basement maybe a foot or two prior to the primary manifold? The OWB is going to be slightly uphill of the house and obviously up in elevation from the basement.

Extra runs of 3/4" electrical conduit. Will do. Thanks for the tips.

I'll make my manifolds as described then. I figured that way, I could easily expand and add more zones if necessary without totally rebuilding the manifold. Just remove the endcap and add another nipple and T and I have a new zone (or a place to put a thermometer or pressure gauge).

I'm not sure you are quite understanding what I meant... There are two different approaches to doing the plumbing, and each has it's own advocates, and it's own advantages and disadvantages.

In "Primary / Secondary" or P/S layouts, while there are variants, the simplest, which is all I think you would need, you would have one loop (the Primary) going from the OWB to the house and back, with one pump to move the water through that loop. At whatever point where you want to have your takeoffs, you put one or more pairs of "close-spaced-tees" which feed Secondary loops that go to the zones and back, each with their own pump. This provides hydraulic separation between the boiler loop and the secondary loops, and is a very elegant approach, though it takes a while to wrap your head around how it works...

The way I'd do the controls in your setup would be to use single speed pumps, or possibly a temp controlled variable speed on the primary loop, and single speed pumps on the secondaries, and have the thermostat for a zone turn on the zone pump, and have the primary loop pump turn on when any zone called for heat. There would be some nuances about how you arranged the zone takeoffs, and so on, but it would be quite workable. Expansion would just mean pulling one end off the manifold and adding another pair of tees.

In the supply return approach, you have a separate manifold on the supply and return lines from the OWB, with your zones going between the manifolds, and controlled by zone valves. A ZV is essentially just an electrically controlled on/off flow control valve. There is just one pump on the boiler lines, which forces the water through the zones when the ZV opens. Downside is that because the flow constantly varies as the ZV's open and close, you need to use either a pressure controlled pump or put a pressure bypass valve between the manifolds to avoid getting excess flow through a zone if only one ZV is open.

Control would be thermostat tells the ZV to open, any ZV opening turns on the pump.

In either setup, given that you said the boiler is slightly uphill from the house, I'd put the pump on the supply line where it enters the basement. This will help deal with the issue many OWB setups have with a lack of NPSH (Net Positive Suction Head, or pressure at the pump intake) causing pump destroying cavitation. It will also make the pump easier to service if need be.

On the pump selection - in the "Tidbits" sticky at the top of the forum page, I have a link to a Taco technical reference paper on how to pick a pump - essentially you need to crank through the math (which starts by needing a heat loss calculation...) and figure out your head pressures, and pick a pump to match...

On the domestic stuff, glad you are ditching the domestic coil... I'd look more at a "sidearm" style HX - I like those a lot more for DHW applications - they seem to have less problem with deposits building up in them than flat plates, and often you can either build them yourself, or purchase them for less than a flat plate, and you don't need a pump on the DHW side if they are plumbed properly. Assuming you hook it up right, and have an appropriately sized DHW tank (You can use your electric water heater for this) then you should have no trouble getting enough hot water during heating season. You would need to put a "tempering" or mix valve on the DHW tank output to prevent delivering dangerously hot water to your faucets.

You could do a DHW setup either off it's own zone, or in line with the W/A HX for the house. Putting it on the same zone as the W/A HX would be simpler and cheaper, but might not get you enough hot water, especially during "shoulder season" when the house isn't calling for that much heat. Doing a separate zone is a little more complex, but would allow the DHW tank to call for heat, even when the rest of the house isn't.

Gooserider

 

[juddspaintballs]

Thank you, that really explained it to me a lot better. Originally I had in my head a thought of a P/S setup using multiple pumps like you say is the more elegant approach. Then you mentioned something about zone valves and it clicked in my head to have the two manifolds, one on the supply and one on the return with zone valves controlling which zone the flow goes through. That seemed simpler up front, until I realized zone valves are just as complicated as multiple pumps.

If I went with a P/S setup, which I now mostly understand, I'd need one pump on the 1.25" lines, and then a pump per zone sized for each zone. Would each zone pump isolate the zone from the primary loop if the pump was not running or would I still need a zone valve too?

If I went with a manifold on both the supply and return lines and zones connecting them, then would a pump like the variable speed Taco 0013 manage the flow correctly so all I would need is a zone valve per zone? I'd probably just let the DHW run without an automatic zone valve so the pump can always circulate water through that zone and keep my water warm as I use it. I'd use a ball valve on it, of course.

I'll try to do a drawing later tonight of what I'm thinking.

 

[Gooserider]

Thank you, that really explained it to me a lot better. Originally I had in my head a thought of a P/S setup using multiple pumps like you say is the more elegant approach. Then you mentioned something about zone valves and it clicked in my head to have the two manifolds, one on the supply and one on the return with zone valves controlling which zone the flow goes through. That seemed simpler up front, until I realized zone valves are just as complicated as multiple pumps.

I would tend to say that ZV's are just different than pumps - they are each about equally complex in their own different way...

If I went with a P/S setup, which I now mostly understand, I'd need one pump on the 1.25" lines, and then a pump per zone sized for each zone.

Correct. The Primary loop pump has to be sized to be able to deliver enough BTU's to feed all the zones at once, but since all you are dealing with is the head resistance of the primary loop, often that doesn't take a huge pump. If you use a temp controlled variable speed pump on that loop then the pump speed changes to supply only the BTU's needed for that specific loop. The secondary pumps are just sized for their own loads, which usually means they are pretty small.

Would each zone pump isolate the zone from the primary loop if the pump was not running or would I still need a zone valve too?

The idea in P/S plumbing is that the secondary tees are close enough together that there is effectively no pressure differential between them, and thus no flow, unless the loop pump is running. It's sort of like why birds can sit on a power line w/o getting fried... If the pump IS running, it pulls water out of the first tee, and returns the exact same amount at the second, so the flow in the primary loop is totally unchanged, other than the water being cooler. In practice, plumbing never quite works in practice as nicely as theory says it should, so you MAY have a potential for some "ghost flow" in the secondary loop, but this can usually be stopped by putting a thermal trap loop on the Tee drops, and a flow check valve in the pump. You shouldn't ever need a zone valve in a simple P/S setup.

If I went with a manifold on both the supply and return lines and zones connecting them, then would a pump like the variable speed Taco 0013 manage the flow correctly so all I would need is a zone valve per zone? I'd probably just let the DHW run without an automatic zone valve so the pump can always circulate water through that zone and keep my water warm as I use it. I'd use a ball valve on it, of course.

The 0013 is a really high power draw pump, hopefully you'd be able to get your head numbers down a lot lower, so as to need a less Watt-hungry pump... (This is one of the claimed advantages of P/S piping - it allows the use of smaller pumps)

I'm not an expert on it, but my impression is that the Taco variables, which operate on temperature are better suited for P/S systems where the pressure demand never changes, but the temperature load does. OTOH, for a ZV system, I would be more inclined to look at the pressure controlled pumps, such as the Grundfos units.

I'll try to do a drawing later tonight of what I'm thinking.

Sounds good.

Gooserider