New build, help me fill my shopping cart

[burn_your_money]

This is my first time building a boiler system so I'd appreciate a bit of guidance on my setup.

I have a Benjamin DO 110 indoor wood boiler hooked in series to a ARGO 20kw electric boiler. The heat dumps into ~1000 gallons of unpressurized storage through a rad submerged in the tank. There is another rad in the tank that supplies heat to my in floor loops. I'm pretty sure I want to use injection pumping with a Tekmar 365 for ODR. I need to order pumps, air eliminators etc and that is what I'm looking for advice on.

This is what I'm planning to build



My floors are 1/2 PEX embedded in 1" thick concrete that is 4" wide. Directly above that is 3/4" pine flooring. I have 4 loops.





For this year, I'm only running 1 zone. I plan to adjust flow through each loop to balance the temperatures and see how we like that.

With the Tekmar 356, do I need a thermostat and if so, what does it control? My understanding of it is that the Tekmar 356 adjusts the temperature in the floor to match outside temperatures by injecting more or less heat into the circuit. The secondary pump (0015e3) is always running.

Am I correct in using a Taco 007 (and not at 007e) for the injection pump with the Tekmar 356?

Regarding my boiler circuit, is there any advantage to using a 007e compared to the 007? What would be the best way to control this pump? I plan on running my storage from 100*F to 160*F. I don't plan on using the electric boiler except when we are away for a few days.

Thank you in advance for your help.

 

[maple1]

I don't have in-floor so I'm not sure about much of anything you asked about, but I think from looking at your diagram I would put the electric boiler over on the other side with your heat loads.

How much of this system is in use? Or is any of it yet? Have you actually used your wood boiler yet? Good luck with it, anyway - I had a Benjamin wood/oil unit for 17 years that was a real pig, it wouldn't have had any extra heat to send to storage to start with. That thing had me absolutely worn out by the time winter was over, every year.

 

[burn_your_money]

Nothing is operational yet.

What would be the advantage of putting the electric boiler on the other side? I think it would cost me more plumbing and a pump. If I have to use the electric, I plan to only run it at night (off peak) and charge the storage. 1000 gallons should carry me through the day at design conditions.

I've heard that the wood/oil units aren't as good, I'm hoping mine will work well enough with the storage. I couldn't find any indoor gasification units that I could afford other than one with terrible reviews. Longer term I'd like an OWB or PV solar but that's some years down the road.

 

[maple1]

What would be the advantage of putting the electric boiler on the other side? I think it would cost me more plumbing and a pump. If I have to use the electric, I plan to only run it at night (off peak) and charge the storage. 1000 gallons should carry me through the day at design conditions.

Electrically heated water is very expensive. Better to confine it to just the zones it is needed. With storage in between, quite a bit of those high dollar BTUs will get lost in the storage & not make it to your floors. So to speak.

I also have an electric boiler for backup heat. Not used since we put the mini-splits in - but it only circulates to zones and not storage. I think the only 'extra' things needed in my case was a circulator and a couple check valves. But I'm not seeing where anything extra would be needed in yours. You could also likely do with a much smaller one. Mine is 18kw, it short cycles quite a bit when running. Pretty sure a 12kw would do me. But it was cheap. To buy.

 

[Bad LP]

If I needed any electrically heated water I would only use a small buffer tank and I wouldn't think of trying to heat 1000 gallons with it.

Why did you put in all the wood strips then fill the voids with concrete? RFH want mass and you eliminated about half of it. Have you insulated the bottom of the RFH zone? Put in as much as you can.

My entire first floor is RFH and the two second floor baths are also RFH. Both floors are in 1.5" Gypcrete.

 

[__dan]

Just a quick reply, not addressing your request.

I would forget about the Argo 20 kW electric. I would not want to spend the next five years paying off last months electric bill. If you don't have it yet, good. If you already have it, it would probably work better at the bottom of a scrap dumpster.

I have an earlier version of the Tekmar 365 injection pump controller and like it. That variable speed system is made to run with PSC type, permanent split capacitor motors, ie, the Taco 007, only because the ECM type were not available when that control was designed for the market. The current version looks like a Tekmar 356

The new ECM type motors, Taco 007e, Bumblebee, Viridian, are far superior and designed for variable speed inherently. The ECM types have very good torque at low speed which is a weakness of the PSC type, along with great efficiency especially at less than full speed. The ECM types will take over the market.

I don't know if there is an ECM circ with outdoor reset or 0 - 10 volt input, but only because the market has not matured. If you can do with an ECM circ what the Tekmar 356 does with a PSC type 007, that would be the way to go (ECM with outdoor reset, control would have to match to the motor type).

The indoor stat calls the zone circ and with in slab radiant. Tekmar has a dual sensor indoor stat with a slab temp sensor. I would echo the earlier comment about why the wood sleepers. The wood is an insulator when you want the thermal mass and conductivity (more radiant output surface) of more concrete. Floor joist does need to be rated for the extra load. Going with what you have, regular stat to call the zone circ or zone valve would seem to be indicated. Indoor stat would call the zone circ (call for heat) and slave call the injection pump.

I have the primary secondary, Tekmar 365 and Taco 007, outside air reset with variable injection pump control, and like it. Never had trouble with it. Heat plumbing part of it is not my thing.

The boiler loop into the tank, the numbers have to be right to match boiler output to what the closed loop in the tank can dump to storage, asuming the loop is closed from the tank itself. Then probably with boiler return water protection. Assuming the boiler just burns flat out without any modulation, I would be afraid of having to fight with any burn rate mismath and boiler too hot or too cool.

I would just want to build it once for a 25+ year lifetime.

 

[burn_your_money]

Thanks for all the input so far.

The wood sleepers are for weight reduction and also for securing the wood floor to them. The floor is not insulated yet. It's on the list but I'd like to finish wiring the basement first. I have the insulation, just a matter of getting the time to do it.

If I have to heat with electric I want to use the storage so that I can take advantage of off peak rates ($0.065/KWH vs $0.12/KWH). I figured with storage the total electric bill for the year would be $600 once the house is finished. It's no where near finished right now so my heat loss is much higher. Ideally I'm not using electric anyways though.

The storage tank is in my basement so there aren't really any losses. I'm designing it for about 1000 BTU/hr heat loss, which is about what that part of the basement needs for heat anyways (again, once it's finished).

The main reason why I bought the electric boiler was because it was cheap and it came with a pump, expansion tank etc and bunch of copper.

I've been looking for an ODR ECM pump but haven't come across any. I had almost given up on the ODR idea until I stumbled on the Tekmar 356. I appreciate the positive feedback on it. I considered a ODR mixing valve but the logic seemed inferior to the 356.

The rad is oversized for the boiler so I won't have an issue getting heat into storage. The aquastat should provide me with boiler protection correct? Is there a way to wire the boiler pump so that it shuts off when the fire is out? Perhaps hooked up to a thermocouple?

 

[Highbeam]

The electric boiler is just fine. You’ve got to remember that a lot of the US has high electric costs so in those areas it is an expensive fuel. For us, propane is more expensive per btu than electric resistance heat!

 

[TCaldwell]

You need 2 thermocouples, one measuring boiler water temp, the other flue temp.
In theory when a fire starts the flue temp will be lower than the boiler water temp, so you need to time out the flue temp acknowledgement for say 10 minutes. By that time the flue temp will be above the boiler water temp, as the fire finishes the flue temp will decline, getting closer to the boiler water temp. When the flue temp is 10 degrees above the boiler water temp it would open the pump contractor or ssr.
Several pid temp controllers

 

[maple1]

I would still put the electric boiler on the load side. IMO you will burn way more KWH in getting the storage hot enough to send enough BTUs to the loads, through 2 HXs and the water in between them, than you would save in time of day usage. I am also leery about a rad being able to strip enough heat off your boiler flow once storage gets warmish. But dont know anything about your rad, and the Benjamin wont be able to put out a great amount of heat. So maybe? You might be hamstrung right off the bat by your boiler choice. Do you know what your heat load will be?

 

[burn_your_money]

@maple1 Heat load will be 15k btu/hr. Right now it could be 60k btu/hr since the house is unfinished.

I estimated/loosely calculated the rad is capable of over 100k btu/hr with a delta T of 20. Since my peak storage temp is 160 I think I'll be ok. If not, I'll be making another thread. The Benjamin is capable of 80k btu/hr. This is the rad. One of the reviewers is using it how I plan to and he was happy with it.

I don't understand how I'm loosing BTU by using storage for the electric boiler since everything is inside the conditioned space. What am I not seeing?

@TCaldwell Could I also hook the aquastat and a thermocoupler on the chimney in series, similar to how the safety on a furnace works? Ideally I'd want one that opens around 200*F.

@Highbeam Thank you for reminding me, I did the cost analysis and electric (with storage) is the same price as propane or oil in my neck of the woods. I would have just gone with natural gas if it was available here.

 

[TCaldwell]

The reasoning behind the above is that regardless of boiler water temp ( wood load size) the pump would shut off at the correct time. Also with odr and shoulder seasons you’ll have the flexibility for smaller wood loads.

 

[maple1]

I can say with absolute certainty there is no way that boiler will put out that many BTUs. Unless you also include what it puts into the chimney. It is the exact same as what I had, except mine was higher and had an oil burner in the bottom. I estimate my average heat load at 35k btu/hr, and it had its hands totally full trying to cover that, and didn't at times. I would chop that 'spec' by at least half.

 

[maple1]

Also, if the tank is in your envelope, yes BTUs lost from the tank will also stay within your envelope. But they wont all go into your floor. Which I have been assuming is where you really want them. Going through 2 HXs will drop output temps through each one, to some extent. I am also not sure about your rad, quite sure I have read that aluminum is a no-no. And really not sure on what its HX abilities will turn out to be. Frankly, with your end heat load and boiler output, I would likely go with just all one pressurized system with small storage or large buffer tank, and eliminate the HXs. It will take a long time for the Benjamin to heat 1000 gallons. But, we all have different preferences.

Edit: Also it wont necessarily be that you lose BTUs by heating storage electrically. But you would be wasting them. Because there should be no point in sending electric BTUs to storage, since you should be able to recharge storage with wood when you burn again. A whole lot cheaper. That's one of the main reasons for having storage.

 

[__dan]

If I was your contractor I would run the other way. If you tried that as a contractor for someone else you would probably risk jail time and losing your own house in the litigation.

It is your house and you are free to cause yourself all sorts of unneccessary and (truly expensive) trouble. The car radiator should be a big clue of a defect in the thought process.

Assemble all of your premises, guesses, assumptions and test each one for defects. Discard the defective premises (LInus Pauling).

 

[Bad LP]

The reason for using Gypcrete is to reduce weight.
We used Bostitch Adhesive to put the wood down. A test piece removed a section of
Gypcrete.
We were told to keep the PEX at least 12” away from the toilet flange for fear of melting it. We stayed away by using 2X6 blocking all around the flange.

 

[burn_your_money]

@maple1 That's disappointing about the BTU output but I appreciate the info. Can you show me an example of what you mean by running off a buffer tank? If 1000 gallons is too much, I can simply lower my rads and reduce the water volume in the tank. Regarding the aluminum, I think the issue is if it's in contact with copper or if there is also copper in the tank due to galvanic reactions. The only metals I will have in the tank are aluminum and stainless steel.

@__dan Which trouble am I overlooking?

@Bad LP I did look into gypcrete briefly but it exceeded my budget. I forget now but I also think it was heavier than what I did. I'm not sure of the reason why but I read that pine isn't to be glued so that also excluded it. I also read about the toilet flanges. I made sure to keep the concrete back like you did. If I run into issues, my dad tells me that they make rubber ones instead of wax.

 

[Bad LP]

I used engineered flooring for a reason. I have a very famous friend who used solid flooring over RFH and didn’t have issues.

I was told not to exceed 105 loop temps but I am running a max of 108 without issues. I’m also using outdoor reset thru a TACO mixing block. I do forget the programmed design temp. System has worked great for 13 years.

IMO you are getting solid advice here and it would be foolish to second guess it. Again... just my opinion. It gets expensive doing things twice and many of us who have gone thru the experience share valuable learning curves from been there done that.

Why are you committed to open storage? It has never ending maintenance costs. Why not use a primary/secondary loop designed system?
My RFH was in the design of the house from day 1. Adding a wood boiler into the mix came well after move in. There’s a lot I learned along the way and most of it came from here then I have some pretty bright friends in the trade.

 

[maple1]

@maple1 That's disappointing about the BTU output but I appreciate the info. Can you show me an example of what you mean by running off a buffer tank? If 1000 gallons is too much, I can simply lower my rads and reduce the water volume in the tank. Regarding the aluminum, I think the issue is if it's in contact with copper or if there is also copper in the tank due to galvanic reactions. The only metals I will have in the tank are aluminum and stainless steel.

A buffer tank is just another term for small storage tank. Say in the order of 200 gallons or less. As far as I know.

I don't think any storage at all will do you much good if any if your average heat load isn't much less than the boiler output. If your loads will indeed be only 15k/hour, that boiler and some storage may be worthwhile. But if your loads are anything more than 30k/hour, that boiler will have its hands full just servicing the loads. And you will be run ragged in operating it, between staying up too late to stuff it full, and getting up too early to do that again, and reloading every 4 hours, and managing coal buildup and creosote production in between. And that is without having open storage and 2 HXs between the boiler & the loads. Honestly, if I was to pick a wood boiler to use, I think that one would be about the worst one I could pick. Just my 17 years of living with one speaking. If you already have it, you could try it, but I would advise too not spend a whole bunch of time & money in putting a storage setup in place like you have planned before you try it just hooked to loads. Unless you plan it so you could easily swap out this boiler for another better one.

I am still very leery about using that rad, and very curious on your calcs to determine how much heat it can move. I didn't see any info in that link to help with calcing that. I have never seen anyone post of their success in using a setup like that (or even just their experiences), here or anywhere else. Not to say it has never been done, but when that is the case with something, there is usually a good simple reason why.

Even if it was able to move all boiler output to storage that you asked of it, and (generously) estimating 40,000 btu/hr average boiler output, it would take 18 hours to charge that 1000 gallons from room temp to 160. And/or, it would take 19 hours (!) to recharge 1000 gallons from 100 to 160, while also supplying your loads with only 15k btu/hr (a very small load relatively speaking). Of heavy steady burning.

There are also other things missing from your diagram that I'm not sure you know of or not. Like boiler return temp protection, for one.

 

[__dan]

The number one thing you are missing is the fuel cost over the expected life of the install. Roughly throwing numbers on it, a conventionally well built older home I usually figure is doing pretty good at 600 gallons of oil annually (oil heat calcs are not my thing either). More than 600 gallons annually and the house either needs major updating or is a tear down.

600 gallons x $3 / gallons x 25 years is $45,000. It looks like you are an employed working person at the early stage of that life, so you do have $45,000 over the next 25 years to have heat in your house.

For that kind on money you can have a Froling with a 400 gallon pressurized tank, which is how I did my calc and selected my equipment. What was the lower cost over the life of the install.

The days of the McMansion, dinosaurs, and building it twice are gone forever. Guys who have to build it twice are dieing young before their time and before the second install. The older generation could have a McMasion built twice but they are dinosaurs today. No new ones are being born.

Your proposed system will work just fine given enough fuel input and boiler attending. However if you calculate the fuel cost of the proposed system over 25 years , the Froling built once right the first way is the cheaper system by far.

The Froling also comes with 25 million or so in prior design engineering and testing, which you get for the added cost of the factory installations instructions. How is your system cheaper, you have some defective premise that may be found and discarded.

The guy online with the car rad home heating system, as soon as he does that job for the next guy for pay, will lose his job and his house and get a new job attending his court hearings.

Which guy do you want to be.

 

[burn_your_money]

@Bad LP It would have been nice to be able to use engineered hardwood but unfortunately that wasn't an option for us.

I'm here to learn, which means understanding the advice that I'm being given. That's why I'm asking questions. I'll be the one servicing and making changes to the system so I need a solid understanding of why I built it the way I built it. Any advice that makes sense to me and I can afford will be implemented.

I'm committed to open storage for a few reasons. First, I already have all the supplies for it and it's almost complete. Second, I am considering experimenting with solar in the future which will require open storage. Third, I couldn't fit any reasonably sized closed storage into my basement. Fourth, I was quoted $10 000 for 320 gallons of pressurized storage. The ROI on that doesn't exist. Used propane tanks aren't easy to come by here and I'm not really comfortable modifying them.

Also, I read that storage also significantly increases efficiency of a boiler and increases the time between burns. Unfortunately I was basing my calculations on faulty information regarding the boiler output. Thankfully, I plan to replace the boiler in the future, or supplement it with other forms of heat production so longer term my storage won't be oversized.

@maple1 I should be able to reduce the volume of my storage by simply filling the tank less if 1000 gallons proves to be too much (which it certainly seems to be). Regarding creosote, that should be kept to a minimum since the boiler will never be idling right?

Thankfully the winter has been very mild this year. Not sure if that trend will continue or not though. Unfortunately your warning comes too late for me, I already have the Benjamin. All the research that I had done prior to buying pointed to it being a decent non gasser.

I do not want to keep this boiler in my house long term (2 seasons max) so the install will be more temporary in nature. I did plan to move it to my (yet to be built) workshop but I may use a different boiler or possibly move away from wood all together by then.

I forget my original figuring for the rad output but off the top of my head:
Original use: 2000 Honda Civic 106 HP = 270k BTU/hr
Typically 30% of that BTU gets transferred to the coolant = 81k BTU
The ad claims ~40% more efficient (if that can be believed), it's water to water instead of water to air, delta Ts are different as well as GPM.

I have read of others using rads before, I know I'm not a pioneer in this thinking. If you google "hot water heater and car rad" you'll get some results. Here's one for example https://www.physicsforums.com/threads/car-radiator-as-a-heat-exchanger.174605/

Since you have pointed out the large difference in expected vs actual BTU/hr of this boiler, perhaps I will rearrange my plumbing so that only excess BTU (if any) go into storage for later use. However, the system isn't going to be operating at design that often so I may be able to make use of the storage for a large portion of the year...

I do not know what is missing from my diagram, please tell me. That's one of the main reasons for this post. Regarding boiler protection though, doesn't the aquastat provide that since it shuts the pump off at a certain low temperature? I realize this wouldn't work on a unit that had a low volume of water with a high delta T but since this boiler has 31 gallons it should work right?

@__dan Sorry I'm not fully following your thought train, why are we discussing oil prices? Oil up here is closer to $4US/gallon. I have limited cash flow at the moment as well as limited financing available due to other projects. Spending big dollars on a boiler to save $600/year does not make financial sense in my situation. Frankly, with my heat loads a new wood boiler never penciled out compared to electric with storage (shocking, I know), especially considering the extra work/expense that wood brings. I expect to be able to recover what I've spent on this boiler on the resale in a few years and if not, it should have saved me enough to make it worth it since my house is unfinished and my heat loads are significantly higher at the moment.

I promise you I will never install a car rad in someone else's home for pay.

 

[3fordasho]

@maple1 I should be able to reduce the volume of my storage by simply filling the tank less if 1000 gallons proves to be too much (which it certainly seems to be). Regarding creosote, that should be kept to a minimum since the boiler will never be idling right?

Anytime you have a firebox surrounded by water you will have creosote on the walls of that firebox- even gasifiers. The difference is the gasifier will not have any creosote once the smoke passes through the nozzle into the lower chamber, heat exchanger tubes and rest of the exhaust will just be light grey dusty ash that just needs occasional cleaning to maintain transfer efficiency - at least that is how mine is and also assuming the use of 20% or less moisture content wood.

 

[maple1]

On the boiler protection, I am not sure on what you mentioned since you didn't show any and don't know your plans. Your boiler return water needs to stay above 140°. Almost always with storage, you are firing when the bottom of storage is very often much less than that. Have no idea how well your planned setup is going to work, but you could have long periods of boiler hot at the top (or trying its best to be) & cold coming in the bottom. Mine had a bypass leg with another circulator and control. Installers said it was for thermal shock protection. But likely could have served the same purpose. And I think there was something in the manual about that, maybe a diagram to go with it. If your HX works anywhere close to what you are anticipating or hoping, it would be feeding water that is too cold almost constantly to your boiler while charging until storage gets warm enough that it doesn't.

Even though we currently have 2 Civics, I have no idea how much heat they put out or their rads handle. But I am thinking the dTs will be kind of narrow here compared to what it sees in a car. Boiler output maybe 160, storage maybe 100 when depleted. That's dT=60. In a car, coolant maybe 180 and air maybe 70? dT =110. Just one example with random number sets. dT here will get even closer with warmer storage.

I would still encourage electric unit located on & confined to load side. Another factor the way you have it drawn is all electric boiler flow goes through the wood boiler before it goes anywhere - that means some of those $$ BTUs will be going up the wood boiler chimney. A fair amount of them I'd guess.

If the boiler does not idle at all, it should make somewhat less creosote yes. But it is a big balancing act with that unit, between getting the fire burning with a decent burn, and not having most of the BTUs go up and out the pipe - very poor heat exchanging capabilities. And it also makes coals like crazy when burning steady (maybe unless you burn softwood) - you will probably find that after 2-3 hours of a good burn, boiler temps will drop and you will have a half a load of hot coals to try to do something with.

There is nothing really 'wrong' in using open storage. It's just that this boiler is just a bad match for it (bad match for any storage), and I would want very capable and proven heat exchangers in doing so.

 

[Bad LP]

The number one thing you are missing is the fuel cost over the expected life of the install. Roughly throwing numbers on it, a conventionally well built older home I usually figure is doing pretty good at 600 gallons of oil annually (oil heat calcs are not my thing either). More than 600 gallons annually and the house either needs major updating or is a tear down.

600 gallons x $3 / gallons x 25 years is $45,000. It looks like you are an employed working person at the early stage of that life, so you do have $45,000 over the next 25 years to have heat in your house.

For that kind on money you can have a Froling with a 400 gallon pressurized tank, which is how I did my calc and selected my equipment. What was the lower cost over the life of the install.

The days of the McMansion, dinosaurs, and building it twice are gone forever. Guys who have to build it twice are dieing young before their time and before the second install. The older generation could have a McMasion built twice but they are dinosaurs today. No new ones are being born.

Your proposed system will work just fine given enough fuel input and boiler attending. However if you calculate the fuel cost of the proposed system over 25 years , the Froling built once right the first way is the cheaper system by far.

The Froling also comes with 25 million or so in prior design engineering and testing, which you get for the added cost of the factory installations instructions. How is your system cheaper, you have some defective premise that may be found and discarded.

The guy online with the car rad home heating system, as soon as he does that job for the next guy for pay, will lose his job and his house and get a new job attending his court hearings.

Which guy do you want to be.

While I disagree with the 600 gallons of oil comment. The basis for the logic in your post is dead on.

 

[__dan]

Regarding boiler protection though, doesn't the aquastat provide that since it shuts the pump off at a certain low temperature?

Never turn off a boiler circ when the boiler is firing. Constant sufficient flow through the heat exchanger (boiler and load) would be a primary concern. If the Benjamin is a cast iron unit it will be looking for not much more than 10 deg F delta T through the boiler when firing. The smaller cast iron units and steel can tolerate a bit more delta T but it is not a huge number. You would not want the load HX to restrict flow through the boiler under load and stress crack the boiler. Consult the boiler manufacturer for recommended and maximun delta T (and minimum flow rate) through their product.

The return protection to raise return water temp over 140 F is a straight bypass of boiler supply water to the return and mix the boiler return temp to at or above 140 F. There are various ways to do it, The Acaso 810 loading unit came with the Froling.

Below 140 deg F will cause flue gas condensation in the boiler and much more of a mess.

Doing it for pay, doing it for other people who would depend, and doing it for the next buyer all fall into the same category, but you are getting the message so the purpose is served. You could sell the Benny sooner rather than later and ride through just fine on electric baseboards if you like that for a fuel. Getting your insulation and windows in would probably be first.

It is easier than ever to do it right the first time because of the much better materials available and easier access to info, but far fewer second chances than the prior generation would get.