Garn It!

[rvtgr8]

I have decided to open another thread on my garn installation. Thanks to so many of the participants, especially Jim K. and Slowzuki, I think that I can safely say that I am seeing light at the end of the tunnel. The details of my plight, of which I am the only one to blame, can be found in the thread, “Garn 1500 Arrived - Can’t afford to hook it up.” I won’t bother people here with my mistakes.

Okay, the existing boiler in my house is a three year old Burnham - Series 2 (Model B) Gas - Fired Boiler using propane (136 K btu). I have been unable to find any part numbers or serial numbers. The system includes a sidearm water heater and zoned in-floor radiant heat. The Pex in the floor is on 12” centers in the middle of 4” reinforced concrete. There is an insulating layer of Poly-iso foam between the slab and the ground. The house is three years old, built entirely by my wife and me.

The house is 2,700 s.f. It has a steel frame with 8” cavity walls blown solid with cellulose. I sheathed both inside and outside of the walls with 5/8 OSB. I have 39 dbl pane windows (low E) and have installed dbl walled polycarbonate interior storm windows on each. We have a Vermont Castings Reliant wood stove which we use to augment the home heating. We keep the thermostats at 60* year round. They are standard Honeywell (no frills) units. We have Ponderosa pine firewood for free from our sixty acres. We are at 7,300 feet, with temps between 90* and -15*. Snows are brutal when they come and many years we have 160”. We average between 1,400 and 1,500 gals. of propane for the entire year. Winter takes about 800 - 900 gals. of the total amount.

The design on the current radiant system hooked to the existing boiler is a question mark for a couple of reasons. The man who designed it did not put in mixing valves. The boiler appears to be set for a range of 128* to 168*. This is the drawing of the existing system. Forgive my homespun CAD work.

I have purchased a Garn 1500 and due to budget constraints must install it myself. I only set aside $2500 and my installer wants $8K. I am not being critical of the installer. He believes that it is a fair price, and it may be, but I do not have the cash.

The Garn will be installed in my new boiler room that used to be my garage. The old boiler room is adjacent to the new one so I have only to cut through a single wall to hook into the Garn. No excavation will be required until some future project comes online. My hot tub and a single radiator will be added into a new room that was my second stall in the garage. Thanks to Jim K, I have now designed a system that just might actually work with efficiency. I am including it here.

My first question is how do I deal with the temperatures in my existing system which appear to be too high because of the lack of mixing valves? Should I place a mixing valve on each of the old zones? The rooms never over or under heat when we use our boiler.

The next question is about sizing on the primary loop on the Garn. Is 1¼” black steel sufficient?

This is probably too much for a first post. I am working on questions and an improved drawing of the new system for later.

Fire away!

Robert

 

[Sting]

Cheese and Rice -- With drawings like that -- i should be asking you for advice

Let me take a stab at this on thing

"My first question is how do I deal with the temperatures in my existing system which appear to be too high because of the lack of mixing valves? Should I place a mixing valve on each of the old zones? The rooms never over or under heat when we use our boiler."

Simply choke (partially close) one of those fine shutoff valves you have in each zone loop to reduce the amount of energy your sending to the load and create the desired Delta T-- that's a simple way - in place of a nice automatic valve! -- Now you may have to play with this -- open the valve a "smidge" bit when the primary loop is circulating cooler water in the warmer part of the season and maybe not.

Kind Regards
Sting

 

[Jim K in PA]

Robert,

If the radiator loop you are showing is for a single radiator, then I do not think you need to make a seperate loop just for that. I would run the return line from your hot tub through a BB rad or an old fashioned cast iron radiator to keep the hot tub area comfortable. That will simplify things. I also think you may find that the standby losses from the GARN itself will keep the garage area comfortable, depending on how well insulated the garage is.

As for primary pipe loop sizing, this is really dictated by the total Btu load you need to feed (GPM you need to pump). However, I would suggest not less than 1-1/2" primary piping, and 1-1/4" secondary piping to the HX for the house. The greenhouse may also need as much diameter, depending on the heat loss. Have you done the calcs for it yet? The hot tub can probably get by with a 1/2" loop, depending on it's size, but I would pipe it with 3/4" for comfort.

Your getting closer!

 

[heaterman]

[quote author="rvtgr8" date="1231631791"]I have decided to open another thread on my garn installation. Thanks to so many of the participants, especially Jim K. and Slowzuki, I think that I can safely say that I am seeing light at the end of the tunnel. The details of my plight, of which I am the only one to blame, can be found in the thread, “Garn 1500 Arrived - Can’t afford to hook it up.” I won’t bother people here with my mistakes.

Okay, the existing boiler in my house is a three year old Burnham - Series 2 (Model B) Gas - Fired Boiler using propane (136 K btu). I have been unable to find any part numbers or serial numbers. The system includes a sidearm water heater and zoned in-floor radiant heat. The Pex in the floor is on 12” centers in the middle of 4” reinforced concrete. There is an insulating layer of Poly-iso foam between the slab and the ground. The house is three years old, built entirely by my wife and me.

The house is 2,700 s.f. It has a steel frame with 8” cavity walls blown solid with cellulose. I sheathed both inside and outside of the walls with 5/8 OSB. I have 39 dbl pane windows (low E) and have installed dbl walled polycarbonate interior storm windows on each. We have a Vermont Castings Reliant wood stove which we use to augment the home heating. We keep the thermostats at 60* year round. They are standard Honeywell (no frills) units. We have Ponderosa pine firewood for free from our sixty acres. We are at 7,300 feet, with temps between 90* and -15*. Snows are brutal when they come and many years we have 160”. We average between 1,400 and 1,500 gals. of propane for the entire year. Winter takes about 800 - 900 gals. of the total amount.

The design on the current radiant system hooked to the existing boiler is a question mark for a couple of reasons. The man who designed it did not put in mixing valves. The boiler appears to be set for a range of 128* to 168*. This is the drawing of the existing system. Forgive my homespun CAD work.

I have purchased a Garn 1500 and due to budget constraints must install it myself. I only set aside $2500 and my installer wants $8K. I am not being critical of the installer. He believes that it is a fair price, and it may be, but I do not have the cash.

The Garn will be installed in my new boiler room that used to be my garage. The old boiler room is adjacent to the new one so I have only to cut through a single wall to hook into the Garn. No excavation will be required until some future project comes online. My hot tub and a single radiator will be added into a new room that was my second stall in the garage. Thanks to Jim K, I have now designed a system that just might actually work with efficiency. I am including it here.

My first question is how do I deal with the temperatures in my existing system which appear to be too high because of the lack of mixing valves? Should I place a mixing valve on each of the old zones? The rooms never over or under heat when we use our boiler.

The next question is about sizing on the primary loop on the Garn. Is 1¼” black steel sufficient?

This is probably too much for a first post. I am working on questions and an improved drawing of the new system for later.

Fire away!

Robert[/quot


A couple quick thoughts

If all your existing loads are low temp in slab type radiant, install a single mixing valve in the main feeding all of them. Note: you'd want to determine which zone needs the highest temp and set the M/V accordingly. You may want to incorporate some type of boiler protection for the Burnham at that point also. They have diagrams of several methods in their Heating Helper listed on the Burnham website.
Come to think of it..........Now might be a good time to consider installing a variable speed mixing circ which would temper the water going to the zones and protect your gas boiler.

I think you'd want to isolate the garn on one side of the HX and take your additional loads (greenhouse,tub etc) from the pressurized side of the system. This will prevent O2 infiltration from as much of the system as possible.

Those are just first quick glance impressions. I'll try to study it further when if I get some time. (doubtful given the weather forecast for next week. C-C-C-C-Cold

 

[rvtgr8]

Jim K and Heaterman,

Here is another drawing. I put the hot tub and radiator on the pressurized house loop. I replaced my Taco 007 with the suggested mixing circulator and in the process got the system pumping away from the boiler. If this would work, any suggestion on a model, sz, etc.? Am I correct in assuming that the Burnham will only fire if the temperature drops below its set range and so as long as I am stoking the Garn, then it will be the only heat source?

Jim K, I have not figured the needs for the green house yet. It will be partly passive solar with several thousand gallons of water absorbing btu's during the day and giving them back at night. I am not going for much more than keeping the thing from going below freezing. It will be a 24'x48' poly-carbonate job with a well insulated foundation and north wall.

Fire away!

Robert

 

[rvtgr8]

Another question that I have is when I Run the hot tub and the radiator on the same zone it should be parallel as I have drawn and not in series? :-S

 

[in hot water]

why not the Garn hx in parallel with the Burnham? No reason the flow through the un-fired Burnham.

hr

 

[slowzuki]

Robert I left some Q's in the other thread for you before I noticed this thread.

 

[slowzuki]

I'll try to post my simplification points, we need to solve overall what we are doing before detailing the system:

-The system is working right now, we should be careful about what we are fixing with a mixdown. If the current system runs anywhere near 100% of the time with the high water temps, we can't reduce the water temp used. Thats why I'm asking about duty cycle in the other thread. Also, if it runs well with little overshoot at high temps, and a low duty cycle, we will probably be ok at lower temps and a longer duty cycle.

-All the new small loads are high temp loads, so why should we be making loops that are great for mixing down to lower temps. We have a huge mixing tank in the Garn that changes temp fairly slowly and all the loads can be designed for some lowest temp that the Garn tank will get down too. The garn tank is basically a large primary loop with a constant natural circulator.

-That said, the flat plate hx will be the most challenging component. At low temps in the Garn, if the interior zones are designed to need high temp, the zone valves will be open at nearly 100% duty cycle to get the heat out of the loop and if the gas boiler is left to run off an aqua stat it will turn on whenever the Garn is getting cool while the rooms are still getting enough heat. I'm guessing a fancier thermostat will be needed or a second one that can call for reserve heat in the gas boiler. Also an aquastat in the Garn could be used to control the switchover.

 

[rvtgr8]

Slowzuki, That's the thing, the zones do not run all of the time. It's 20* out right now with 25 mph winds. I went out and checked the boiler. The side arm had no call and was not running. My back rooms were not running and they are on the same zone. Two zones kicked in while I was watching and one of those was on the wind side of the house, while the other is our sunroom where we keep our parrots.

We never had the system run at temps over 60* in an attempt to save propane. I am not able to ascertain how the old system would be impacted by a HX running at higher or lower temps, but I was hoping the the mixing circulator in place of my Taco 007 would give me the flexibility to adjust temps to appropriate levels. Am I way off base here?

In Hot Water, your intuition was the same as mine initially, but not being an engineer, I have deferred to several very smart Garngaroos who suggested that I use a primary loop as I have shown. This is the problem with being a newbie to hydronics, everybody knows so much more than I do. When I joined, I thought Delta T was a reference to the actress Delta Burke. I was unaware of her unheralded skills as a boiler maven.

 

[Jim K in PA]

I'll try not to confuse or obfuscate (love that word), so I'll defer to others more competent than I, but I suggest the simplest system usually works best. Given that Robert has a gas fired boiler with a low set of 128, I think he will be just fine with his GARN running down to 135 before he fires it, and before the low set of the Burnham kicks it on (he can lower it more, perhaps).

Robert - simplify the primary loop. You have two pumps where only 1 is needed. Do not pipe the GARN as a secondary - it should be in series with the primary loop. Pipe out - pump - secondary load tees - pipe back into GARN.

You left out the circ pump for the GH. No biggie.

HX sizing will be key. In order to keep the Burnham from reaching low setpoint when the GARN temps are less than 20 degrees above that set point, the HX must be able to transfer efficiently at those lower temps. More surface area will be needed. Size of the HX will be MUCH larger than you might estimate based on peak AVERAGE load. Instantaneous peaks, where you have most or all zones all calling, wind blowing , shower running, etc., is where you might find the Burnham kicking in to supplement if the HX is not loading enough heat into the house side. Do you care if the propane unit kicks on 5% of the time? If not, then no worries. Honestly, I think with a radiant system, you can get along just fine with short term dips in water temp (minutes, not hours).

I am thinking 70 plate 5x12, at least, for all his present and future loads. This component will be the next largest single purchase after the GARN itself in your system. Check eBay for KJmotorsports - he has good prices and shipping is free. I just bought my 50 plate from Kyle.

 

[slowzuki]

1. That is good, gives you options in your setup.

2. The HX will need to be sized (we'll help) such that on the coldest day with the Garn at the lowest target temp, you can still keep the house at your set temperature. The lowest temp we can run the Garn down to will be determined by the PEX already in the slab in that once the zone is open and flowing full tilt, a correct hx installed, the only thing you can play with is water temp.

3. Your intuition is right, simpler is better to a point. The primary secondary is a good way of connecting several loads and heat sources that are going to be in use simultaneously without having to think hard. It lets you look at each one individually and saves creating accidental problems. It is however not the simplest is some cases.

Slowzuki, That's the thing, the zones do not run all of the time. It's 20* out right now with 25 mph winds. I went out and checked the boiler. The side arm had no call and was not running. My back rooms were not running and they are on the same zone. Two zones kicked in while I was watching and one of those was on the wind side of the house, while the other is our sunroom where we keep our parrots.

We never had the system run at temps over 60* in an attempt to save propane. I am not able to ascertain how the old system would be impacted by a HX running at higher or lower temps, but I was hoping the the mixing circulator in place of my Taco 007 would give me the flexibility to adjust temps to appropriate levels. Am I way off base here?

In Hot Water, your intuition was the same as mine initially, but not being an engineer, I have deferred to several very smart Garngaroos who suggested that I use a primary loop as I have shown. This is the problem with being a newbie to hydronics, everybody knows so much more than I do. When I joined, I thought Delta T was a reference to the actress Delta Burke. I was unaware of her unheralded skills as a boiler maven.

 

[slowzuki]

1. Agreed simple is better. I'm not convinced on the existing boiler, I think it will get a bunch of short cycles while the HX comes up to temp from the Garn.

2. The primary loop already existing inside the Garn. Why try to complicate it? As long as the Garn has some large diameter tappings, you can install a short fat manifold directly to the Garn.
EDIT I see what you are saying. I'm sort of saying the same thing. I was thinking manifold but if you incorperate the HX into a primary loop you can put the new loads on the loop. That will force the main circulator to run all the time. Not so good in the summer as it will have more wasted heat.

3. Agreed the HX will be big.

I'll try not to confuse or obfuscate (love that word), so I'll defer to others more competent than I, but I suggest the simplest system usually works best. Given that Robert has a gas fired boiler with a low set of 128, I think he will be just fine with his GARN running down to 135 before he fires it, and before the low set of the Burnham kicks it on (he can lower it more, perhaps).

Robert - simplify the primary loop. You have two pumps where only 1 is needed. Do not pipe the GARN as a secondary - it should be in series with the primary loop. Pipe out - pump - secondary load tees - pipe back into GARN.

You left out the circ pump for the GH. No biggie.

HX sizing will be key. In order to keep the Burnham from reaching low setpoint when the GARN temps are less than 20 degrees above that set point, the HX must be able to transfer efficiently at those lower temps. More surface area will be needed. Size of the HX will be MUCH larger than you might estimate based on peak AVERAGE load. Instantaneous peaks, where you have most or all zones all calling, wind blowing , shower running, etc., is where you might find the Burnham kicking in to supplement if the HX is not loading enough heat into the house side. Do you care if the propane unit kicks on 5% of the time? If not, then no worries. Honestly, I think with a radiant system, you can get along just fine with short term dips in water temp (minutes, not hours).

I am thinking 70 plate 5x12, at least, for all his present and future loads. This component will be the next largest single purchase after the GARN itself in your system. Check eBay for KJmotorsports - he has good prices and shipping is free. I just bought my 50 plate from Kyle.

 

[slowzuki]

Using a pump or valve to mix down the temps at the house has benefits but I don't think it is a priority right now for getting the system up and running on a minimal budget. 2500$ is gonna take a hit from the flat plate purchase. And the non-ferrous pumps on the Garn side are fairly pricey too.

 

[rvtgr8]

Okay, primary loop changed, greenhouse circulator in place and 70 plate HX "in da howse!"

Slowzuki, were you saying you liked the idea of a mixing circulator pump to control temps in the old system?

 

[slowzuki]

Robert,

Protecting your old boiler with a mixing device or even providing mixed water to your slab are nice features to have, but they are off track of getting your system up and running since it works already. I'd suggest adding them later after getting the Garn running. There are a number of ways of doing it and some can move your gas boiler out of the loop in case you don't want it to be heated too.

Your newest sketch is exactly what Jim is talking about. My suggestion is only to eliminate the loop off the Garn and install a pair of short fat manifolds (one supply, one return) at the Garn and use pumps with flow checks to prevent them from ghost flowing in reverse. All the Garn zones would be in parallel.

 

[rvtgr8]

Slowzuki, I just read your comments that you posted on the other thread and have included them here. I wanted to give you the most accurate picture I can. I went out to test the system. This is what I did:

1] again, it is a cold windy day (22* with gusty winds 25mph and 4" snow but now sunny). We have a fire going in our VC Defiant. Thermostats are all set at sixty. The house is about 70* with the fire and the solar gain in the sunroom. As you might expect, there was no heat call anywhere in the house and so the system was inactive, including my trusty Taco 007.
2] I hand felt all of the zones and they had obviously been off for some time because they were cool.
3] I turned on a utility sink in our mudroom to put a call on our side arm water heater. After several minutes the boiler came on, the Taco came on and water began to circulate. The pipes on that zone quickly became too hot to comfortably hold on to.
4] No other zones came on.
5] There are no noises other than the obvious clicks when the electric valves open. The Taco is so quiet that I can only hear it when I place a rod on the motor and place my ear on the other end.

Hope this helps

Robert

Hi Robert,
I think it is entirely reasonable to achieve what you want to do on the budget, the question will be how fancy to get with it, and how many of the other toys you want to hook in immediately. I’ve got a few questions for you about your current setup so we can help you more.

When it is cold out, do you know roughly what percentage of the time your circulator runs or zone valves run? Since you have basic thermostats I’m assuming it is wired to open the zone valve and start the pump or it may be wired to run the pump continuous and the t-stat just runs the zone valve.

Being its cold up there it may not be a problem, but if its warm, say from your stove, and no zones are calling for heat, do you have noises when a zone calls for heat? Some times happens when there is no relief valve between the manifolds from the zone valve slamming. This would be more common in shoulder seasons.

Once we figure this stuff out we can try to solve the plumbing.

I don’t think you’ll have a terrible problem with your gas boiler since its a high mass unit (cast iron hx) and you probably aren’t using it to capacity. We just would like to do what we can to protect it. I assume right now you get your hot water off it with a coil?

Thanks,
Ken

 

[rvtgr8]

Ken, is this sort of what you are talking about?

 

[Jim K in PA]

Ken - you and I are now in full understanding of each other, I think. I think you and I are skinning the cat in two slightly different ways, but getting to the same point. As far as the primary pump having to run continuously, that is not necessarily so. I solved that issue with a TACO Zone Valve Controller and a TACO Switching Relay Controller. Any zone on the house triggers the end switch on the ZVC, which then triggers the circ on the house loop. The SRC has an end switch that starts the primary pump whenever any secondary pump is energized. The units are not cheap, but not bad either (~$190 each).

I am also not convinced that bronze pumps are an absolute necessity in a GARN application. Although technically an "open" system because it is not pressurized, there is no appreciable O2 reuptake unless you are refilling due to a leak. Standard ferrous pumps are perfectly OK, IMO.

 

[slowzuki]

Hi Robert and Jim,

Robert, you are getting close but not quite. I'll try a sketch.

Jim, yes, a zone controller could nicely handle the logic of starting the Garn from the calls for heat in the house. This could also be done with some wiring and a couple of relays but for Robert the controller might be easier.

I also agree the bronze pumps are not required with boiler treatment. I was thinking of the stainless Garn copy another fellow on here has, normal Garns are steel. A stainless tank without treatment would end up attacking a ferrous pump.

I'll add a sketch to here in a few minutes.

Ok please take it easy on me, I'm on a broken touch pad, with no mouse! But you get the idea. The suction manifold has to be as large as the tapping on the Garn allows and as short as physically possible while allowing the pumps to be a couple of feet lower than the water level so they don't have suction issues.

Each pump is sized by the duty it is doing. The HX pump will be fairly large. The start signal for your current large circulator can be sent to an aquastat on the Garn with a low temp cutoff and then to the HX pump so if the Garn is cold the HX pump won't run.

 

[rvtgr8]

Ken, is this close to what your drawing is trying to illustrate?

 

[Rick Stanley]

I have been cautioned by Garn (the dealer, the manual and Lunde) to keep the Garn pumps as close to the floor as possible and to have 6 ft of black iron between the Garn and the first yellow metal.

Rick

 

[slowzuki]

Robert yes it is. Thanks for cleaning it up!

Based on what Rick is saying it sounds like the tapping on the Garn might not be very big. In that case, yes, you need to get you pumps down low so the head from the water in the tank always keeps them from cavitating. Any one have any info on the Garn's tappings?

Regarding the connection of copper to a steel boiler, in practice its usually ok to connect a small amount of brass or copper to large steel system especially with teflon tape / pipe dope between. If you have a lot of copper, dielectric unions can help reduce corrosion of the steel, they aren't perfect though. Cheap brass with lots of zinc in it can have the zinc stripped right out of it as it acts like an anode to the steel.

Some boiler treatments can reduce the corrosion of metals that aren't compatible, the galvanic potentials of the metals is affected by what electrolyte they are in.

 

[Jim K in PA]

The GARN tappings are 2" upper (supply) and 1.5" lower (return).

The location of the pumps is important, and I may have to lower mine. I have my primary pump at about 30" above the floor. If I get the water temps above 195, I start to hear "suction boiling" in the pump. I usually keep my temps below 190 for that reason. I will probably re-pipe the pumps lower next summer. I can actually get my pumps below the bottom of the GARN, as I run them in my garage, the floor level of which is about 3' below grade where the GARN sits.

 

[slowzuki]

Jim do you have 2" with a minimal number of fittings up to the suction side of your pumps and is your main pump high capacity? It doesn't take many fittings to add friction.

The GARN tappings are 2" upper (supply) and 1.5" lower (return).

The location of the pumps is important, and I may have to lower mine. I have my primary pump at about 30" above the floor. If I get the water temps above 195, I start to hear "suction boiling" in the pump. I usually keep my temps below 190 for that reason. I will probably re-pipe the pumps lower next summer. I can actually get my pumps below the bottom of the GARN, as I run them in my garage, the floor level of which is about 3' below grade where the GARN sits.