Requesting New Boiler Upgrade Design Help

[Newfiestang]

Folks, I am in the process of trying to design an install of a new Gasifier wood boiler system to be mated with my existing oil boiler. Prior to doing anything I am attempting to calculate my homes heat loss.

I've seen several web based calculators but I have stumbled across the Taco FlowPro design software and have been playing around with it for a few days now. I've sketched my floor-plan in the software and came up with a heat loss of 33800 btu/hr. Can someone please tell me if this seems out to lunch or is it reasonable.

My home is approx 15 years old, single story with basement consisting of 8' concrete walls. The home is constructed of typical building standards of the time, 2x6 framing, insulated R12 walls, R20 ceiling. The home is 1653 sq ft on main level and same in basement. windows are dual pane single, average size of windows are 35w x 60"h and there are about of these on the main level. Other items are the normal insulated steel doors, patio door....etc.

I know this is a tough question to answer and im not expecting anyone to sit down to calculate this but just wondering if this seems like a reasonable number. I have been looking at the Attack DPX boilers and been in discussion with New Horizon in the US and they are thinking that the DPX 35 with 500 gallons of storage will be fine but this seems a little small to me......but im no expert by any stretch.

I am currently heating the home with a New Yorker WF 100 wood boiler and does just fine but its not very efficient thus the upgrade.

I have attached a floor plan of both the main level and basement showing the heat loss calc for both levels.



Anyway any info you guys can provide would be great. Thanks in advance.

 

[Bob Rohr]

A rough rule of thumb for a home constructed like that would be 20- 25 BTU/sq. ft. so 1653 X 20= 33060, so you load number is believable.

If that boiler is a 35 KW X 3.41= 119,000 X 80% efficiency = around 95,000 BTU/ hr actual output at full fire, plenty of power to heat your space, up and downstairs.

Of course the heat emitters need to be sized to the load also, fin tube, radiators, fan coil whatever you decide.

A buffer will be critical since you have more boiler output then required even at design conditions.

Perhaps the New Yorker is rated at 100,00 BTU/hr.? Assume a 50% efficiency, you may only have 50,000BTU/hr output from that unit, or 1/2 of the DPX 35.

 

[Newfiestang]

A rough rule of thumb for a home constructed like that would be 20- 25 BTU/sq. ft. so 1653 X 20= 33060, so you load number is believable.

If that boiler is a 35 KW X 3.41= 119,000 X 80% efficiency = around 95,000 BTU/ hr actual output at full fire, plenty of power to heat your space, up and downstairs.

Of course the heat emitters need to be sized to the load also, fin tube, radiators, fan coil whatever you decide.

A buffer will be critical since you have more boiler output then required even at design conditions.

Perhaps the New Yorker is rated at 100,00 BTU/hr.? Assume a 50% efficiency, you may only have 50,000BTU/hr output from that unit, or 1/2 of the DPX 35.

Just curious about your use of 80% above for efficiency....these boilers claim to be a little over 90%, are you just putting in a safety factory of 10% or am i missing something.

Also, your rough rule of thumb for heat loss is just for main level i guess, with full finished basement we have another 1653 sq ft. From the Taco Software it seems if the heat loss is alot less down there, mainly due to no windows i guess maybe. In either case it seems my heat loss calc for main level would be low compared to yours.....the software is stating 33000 or so for both levels.

Thoughts??

 

[maple1]

My house is similar construction but two story - 1500 on first, 1200 upstairs. Plus 1500 in unfinished basement. On an exposed hilltop. I burn roughly average 6 hours per day thru the winter, with my 40kw (136,000 btu) rated boiler. It's tied to 660 gallons of water. That all works out to 34,000 btu/hr - neglecting efficiency losses. So I would also say your numbers are safe.

My seat of the pants assessment is that if your New Yorker heats your place fine, a gasifier would do much better, and a 35kw boiler should handle things easily. I would try to upsize the storage though if you can - my 660 does OK, but would much rather have 1000. But space has been an issue for me.

 

[Newfiestang]

My house is similar construction but two story - 1500 on first, 1200 upstairs. Plus 1500 in unfinished basement. On an exposed hilltop. I burn roughly average 6 hours per day thru the winter, with my 40kw (136,000 btu) rated boiler. It's tied to 660 gallons of water. That all works out to 34,000 btu/hr - neglecting efficiency losses. So I would also say your numbers are safe.

My seat of the pants assessment is that if your New Yorker heats your place fine, a gasifier would do much better, and a 35kw boiler should handle things easily. I would try to up size the storage though if you can - my 660 does OK, but would much rather have 1000. But space has been an issue for me.

Ok well that sounds good. Yes would love to go with more storage but have the same issue...limited space in my basement boiler room. I am looking at the pressurized 240 gal tanks from biothermic here in Canada. Can probably fit 2 for sure but maybe three. These sell here for approx $1300 each plus tax and freight. Looked at un-pressurized tanks as well but time you factor in exchangers and all you are back to the same price-point.

What is the thoughts from most on a pressurized tank system. I know one issue that is see so far with multiple tanks is trying to ensure the water enters both evenly. I'm not a fan of them installed in series but maybe its not a problem.....not sure.

So you say you burn 6hrs a day......do you then run off storage for the remainder of the day with that 660 gal storage.

 

[maple1]

Ok well that sounds good. Yes would love to go with more storage but have the same issue...limited space in my basement boiler room. I am looking at the pressurized 240 gal tanks from biothermic here in Canada. Can probably fit 2 for sure but maybe three. These sell here for approx $1300 each plus tax and freight. Looked at un-pressurized tanks as well but time you factor in exchangers and all you are back to the same price-point.

What is the thoughts from most on a pressurized tank system. I know one issue that is see so far with multiple tanks is trying to ensure the water enters both evenly. I'm not a fan of them installed in series but maybe its not a problem.....not sure.

So you say you burn 6hrs a day......do you then run off storage for the remainder of the day with that 660 gal storage.

Yes - so that works out to average 18 hours on storage. But there are a few little tricks to getting that far on it for me - like lining up your times of burning for when your heat load is the most. Which means light a fire & get it going, then turn the thermostats up a half hour after that & heat the house up a little bit warmer than usual. Then I set back most of my zones about the same time as the fire goes out. So the house works as storage to some extent too. I also usually fully deplete storage before I burn again. When a 40kw (or 35) gasifying boiler is burning, it can put out a lot of heat in a short time, especially when comparing that to an older very inefficient boiler. Which I also used to have.

My storage is pressurized - two stacked 330 used LP tanks. So they are in series - hot in & out at top/one end, cold in & out at bottom/other end. I found a mountain of them in Moncton NB, think I spent around $800 for the two 330s plus a 110. If your tanks are side by each & parallel you should be able to get flows to balance by plumbing simple reverse return configuration. A header between the two top ports, another between two bottom ports. Then your system would T to the top on the left side of the header, and the bottom on the right. Or vice versa. Simply speaking. If you put ball valves on the tank outlets, you should be able to throttle one a little bit if you do end up unbalanced somehow.

 

[Newfiestang]

Yes - so that works out to average 18 hours on storage. But there are a few little tricks to getting that far on it for me - like lining up your times of burning for when your heat load is the most. Which means light a fire & get it going, then turn the thermostats up a half hour after that & heat the house up a little bit warmer than usual. Then I set back most of my zones about the same time as the fire goes out. So the house works as storage to some extent too. I also usually fully deplete storage before I burn again. When a 40kw (or 35) gasifying boiler is burning, it can put out a lot of heat in a short time, especially when comparing that to an older very inefficient boiler. Which I also used to have.

My storage is pressurized - two stacked 330 used LP tanks. So they are in series - hot in & out at top/one end, cold in & out at bottom/other end. I found a mountain of them in Moncton NB, think I spent around $800 for the two 330s plus a 110. If your tanks are side by each & parallel you should be able to get flows to balance by plumbing simple reverse return configuration. A header between the two top ports, another between two bottom ports. Then your system would T to the top on the left side of the header, and the bottom on the right. Or vice versa. Simply speaking. If you put ball valves on the tank outlets, you should be able to throttle one a little bit if you do end up unbalanced somehow.

Excellent info, I would be quite happy with an 18hr run on storage, I cant get any longer than about 4 or 5 hours with the WF 100 im using now. Having said that if you keep the wood to her she heats the house just fine.

So whats the dimensions on the tanks, problem i also have is that whatever it is needs to fit through multiple door openings, most of which are 32" interior doors in my finished basement. The 240 gal ones Biothermic has are 26" in dia. so perfect......price not so much. I was very surprised the cost of the unpressurized tanks from American Solar. The area where these will go is 72" x 79" so the biggest AS tank i could go with was the 550 gal. It cost $2400 US and I still have to buy liners and exchangers.

The other issue I'm afraid of is insurance, I'm not sure if I will be covered period with that much water storage in my basement but with somewhat of a fabricated rig such as yours (no negativity intended) I dont think I would stand a chance.

One more question, do you happen to know where I might find some good piping schematics of a wood, oil, & storage setup. I would also need to incorporate my DHW coil in my oil boiler if possible. Right now both my wood and oil boiler both have DHW coils and I must say its an excellent setup for DHW supply. Not really interested in a separate DWH setup if I can avoid it.

 

[maple1]

I think my tanks were 30" diameter. I have a walk out basement with pretty good access, but had a 90° turn to get around. That was thru a 4' door though, so they went in pretty good. But they are heavy.

Re. American Solartechnics - I am pretty sure you can build your own tank/box to fit your space, and then get a liner from them made to fit?

I would likely dig through the stickies for schematics.

About DHW - I would seriously consider going to an ordinary electric tank type water heater. Heating DHW with an oil boiler in the summer is a losing proposition from experience & what I have heard, it's about the least efficient and most expensive way to do it. You could then heat it in the winter with a heat exchanger from your wood heated water, which is what I do. If your oil unit could stand being shut down for the summer that is. I yanked all our oil stuff out (old boiler also had a coil in it) when I made my boiler change & put in an electric boiler for backup (very infrequent use) and electric DHW tank heater. If we get to not wanting to burn wood in the future, I might consider putting an oil boiler back in (if not something heat pump related) but I won't be doing DHW with oil again, pretty sure about that. Getting rid of the oil tank is also a big bonus for freeing up space and getting rid of liability - we were due for a new tank soon for insurance reasons though which was another factor.

 

[Newfiestang]

I think my tanks were 30" diameter. I have a walk out basement with pretty good access, but had a 90° turn to get around. That was thru a 4' door though, so they went in pretty good. But they are heavy.

Re. American Solartechnics - I am pretty sure you can build your own tank/box to fit your space, and then get a liner from them made to fit?

I would likely dig through the stickies for schematics.

About DHW - I would seriously consider going to an ordinary electric tank type water heater. Heating DHW with an oil boiler in the summer is a losing proposition from experience & what I have heard, it's about the least efficient and most expensive way to do it. You could then heat it in the winter with a heat exchanger from your wood heated water, which is what I do. If your oil unit could stand being shut down for the summer that is. I yanked all our oil stuff out (old boiler also had a coil in it) when I made my boiler change & put in an electric boiler for backup (very infrequent use) and electric DHW tank heater. If we get to not wanting to burn wood in the future, I might consider putting an oil boiler back in (if not something heat pump related) but I won't be doing DHW with oil again, pretty sure about that. Getting rid of the oil tank is also a big bonus for freeing up space and getting rid of liability - we were due for a new tank soon for insurance reasons though which was another factor.

Ya 30" dia would be an issue I think for me.

I will look through the stickies some more, didnt see a whole lot there to be honest. Lots of good info but not too many dwgs. I am foolingaround with the design myself, I am an Instrumentation tech so all this is kind of familiar stuff but its still good to work with experienced folks, im old enough to know how valuable that is.......priceless!!

I'm surprised on your response about the oil for DHW use......we find ours to be ver good for summer DHW supply......but then again got nothing to compare to. Cant see electricity being the way to go at all with our rates......and Muskrat falls project here in the next 5 years will make that price sky-rocket. Going to be alot of people move from electrical use in all aspects if they can. Also, we just installed a new oil tank so investment is made now for another while.

 

[Bob Rohr]

there are a few ways to pipe multiple tanks so the flow evenly, here are some ideas.


https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_17_na.pdf

 

[maple1]

Further on the DHW, we went from between 3/4 and 1 gallons of oil per day, to around $25/mo of $0.18/kwh electricity. For dhw in the summer.

 

[Newfiestang]

Further on the DHW, we went from between 3/4 and 1 gallons of oil per day, to around $25/mo of $0.18/kwh electricity. For dhw in the summer.

Well cant say I really did any close analysis on what it cost me during the summer. In the winter its ideal since both my boilers take care of the DHW. Basically both are equipped with DHW coils piped in series with cold water entering the wood boiler first. See below schematic.for illustration, of my current piping, just picture both boilers with DHW coils.

So that brings me to my issue with this new boiler, it dont have a domestic coil so my DHW now only has one source, the coil in the oil boiler. This I'm struggling with in sketching up the piping....plus the whole storage tank(s) tie in as well. If anyone has anything remotely similar I would appreciate it. Would prefer to not complicate things to much with a whole lot of circulators and 3 way valves, even though it looks like i will need at least 3 pumps and maybe one or two 3 way motorized valves. I have also attached a possible setup that i found on the web but in this arrangement it looks as if the aux (oil) boiler will have to heat the storage if the wood boiler is not lit.....say in summer months. Am I correct in my understanding of this arrangement.

Thanks

 

[Newfiestang]

Well cant say I really did any close analysis on what it cost me during the summer. In the winter its ideal since both my boilers take care of the DHW. Basically both are equipped with DHW coils piped in series with cold water entering the wood boiler first. See below schematic.for illustration, of my current piping, just picture both boilers with DHW coils.

So that brings me to my issue with this new boiler, it dont have a domestic coil so my DHW now only has one source, the coil in the oil boiler. This I'm struggling with in sketching up the piping....plus the whole storage tank(s) tie in as well. If anyone has anything remotely similar I would appreciate it. Would prefer to not complicate things to much with a whole lot of circulators and 3 way valves, even though it looks like i will need at least 3 pumps and maybe one or two 3 way motorized valves. I have also attached a possible setup that i found on the web but in this arrangement it looks as if the aux (oil) boiler will have to heat the storage if the wood boiler is not lit.....say in summer months. Am I correct in my understanding of this arrangement.

Thanks

Folks, any comments on my question above around the DHW supply from my existing oil boiler......and how this can be achieved.

 

[maple1]

Kind of depends on how you are tieing the oil into the new boiler. The backup boiler in the above system won't be heating a lot of that storage, as the heat output from it will go through the top of the storage tank from one end to the other - as long as the temp sensor for its control is sensing at the very top, or somewhere on the supply line. It will heat a bit of it though. Which may not be a terribly bad thing if any heat loss from storage is going into the house anyway. Will you be wanting to let your oil boiler go cold when it is not needed? Not really sure the best approach to use if you aren't going to add a DHW tank - some would put the oil boiler in series so it is kept hot all the time but that would cost you a bit of efficiency.

 

[Hydronics]

Just food for thought: you may want to look at your return on investment. Don't get me wrong, I have a gasifier that works very well. I'm just saying -be honest with the cost/benefit of replacing your existing boiler that seems to be getting the job done. Of course, there is more to consider than finances alone. Good luck

 

[Newfiestang]

Kind of depends on how you are tieing the oil into the new boiler. The backup boiler in the above system won't be heating a lot of that storage, as the heat output from it will go through the top of the storage tank from one end to the other - as long as the temp sensor for its control is sensing at the very top, or somewhere on the supply line. It will heat a bit of it though. Which may not be a terribly bad thing if any heat loss from storage is going into the house anyway. Will you be wanting to let your oil boiler go cold when it is not needed? Not really sure the best approach to use if you aren't going to add a DHW tank - some would put the oil boiler in series so it is kept hot all the time but that would cost you a bit of efficiency.

Maple, I would like for the oil boiler to be in the system in such a way to act as a indirect DHW heater....if you know what i mean, since it has a DHW coil this should work just fine. If i understand correctly to accomplish this the water temp in the oil boiler will have to be measured by a sensor (either via oil boiler controls or external controls) which would in turn operate the oil circulator to energize to keep the oil boiler above the set temp. Once the pump is on then either pull water from the storage or wood boiler if temps in these devices are satisfied. If not the oil boiler will fire. Does this make sense?

I think the below diagram would probably work minus the tankless water heater just after the storage. It seems this arrangement wont allow the oil boiler to heat the storage tank either...which is what i want, cant see that being efficient at today's oil prices where i live. In this diagram i am not certain what control devices I would have to purchase either, for example delta T controller, outdoor reset controller. Are these internal to modern boilers such as the Froling or Attack line.

The other thing in this diagram and some others ive see that i cant get my head around is the closely spaced T's. Does this configuration work, I assume so since its in quite a few piping diags but cant really find much on the principle of operation. Also, I probably wont need the 3-way valve either since I have high temp base board heaters.....correct?

Anyway as always....any input would be appreciated. Got a quote today from a Canadian Supplier for an Attach 35DPX which I am really pleased with but apparently they are not CSA approved...which is a whole other topic. I need a design that works first.

 

[Newfiestang]

Just food for thought: you may want to look at your return on investment. Don't get me wrong, I have a gasifier that works very well. I'm just saying -be honest with the cost/benefit of replacing your existing boiler that seems to be getting the job done. Of course, there is more to consider than finances alone. Good luck

Yes I agree that the return might not be there for sure but my current boiler was purchased used when I built my new home 15 years ago and was about 10 years old then so I cant help but wonder how many years its got left. I am 46 years old with a decent income and would rather take on an expense now while working rather than just before retirement in 10 or so years......just my way of thinking. Plus I am a controls and instrument tech so this has a "cool" factor appeal for me.

 

[Newfiestang]

Another diagram that may work but appears the oil boiler would have to heat the storage tank.

 

[Bob Rohr]

Another diagram that may work but appears the oil boiler would have to heat the storage tank.

View attachment 215363

In this drawing the buffer tank is the source of DHW via the plate HX, so one of the boilers needs to maintain the tank temperature all the time.

 

[Quincy]

Check out craigslist in New Hampshire there is a new vedolux 37 ,storage tanks ,and expansion tanks for sale not sure if that's what your looking . It would be a nice package if the price was right.

 

[Newfiestang]

In this drawing the buffer tank is the source of DHW via the plate HX, so one of the boilers needs to maintain the tank temperature all the time.

Yes thats what i thought, not really interested in the oil boiler doing this duty.

So in the diagram before that with the oil boiler after the storage, do you agree that the oil boiler can provide DHW if the controls can be configured to energize its circulator to pull from storage to maintain say 140 deg in the oil boiler thus providing adequate temp to heat the water passing through the DHW coil in the boiler.

It seems doable to me but while I am quite familiar with controls in my line of work I am not familiar with boiler controls for home heating boilers. I know that the oil boiler has its own aquastate but I cant say if it can be used or configured to achieve what i want here or if there will need to be a separate sensor used somewhere wired to an external controller. This I need help with.

In my existing setup the circulator between the wood and oil boilers run all the time once the wood boiler reaches its set temp and the temp switch closes.....which i currently have set to approx 170deg so not an issue. Once above this temp the second set of contacts of this same temp switch opens and also disables the oil burner.

 

[Newfiestang]

T

Check out craigslist in New Hampshire there is a new vedolux 37 ,storage tanks ,and expansion tanks for sale not sure if that's what your looking . It would be a nice package if the price was right.

Thanks, will check it out but must admit I am kind of stuck to the froling or Attack, must be the color. Only issue I may run into is the Attack is not CSA approved, but it sure is alot cheaper, about $3K less than the Froling FHG 20/30.

I am finding it very difficult to beat the price on ASME approved pressurized tanks at biothermic in Canada, $1300 per 240 gal. These are also the only pressurized tanks I have come across that will fit through regular door openings, they are 26" in diameter.

 

[maple1]

T

Thanks, will check it out but must admit I am kind of stuck to the froling or Attack, must be the color. Only issue I may run into is the Attack is not CSA approved, but it sure is alot cheaper, about $3K less than the Froling FHG 20/30.

I am finding it very difficult to beat the price on ASME approved pressurized tanks at biothermic in Canada, $1300 per 240 gal. These are also the only pressurized tanks I have come across that will fit through regular door openings, they are 26" in diameter.

You might want to run this stuff past your insurance guy. The only thing mine told me is as long as the boiler has a CSA sticker you're good. $3k might not be so bad to step up to a Froling.

Did you check out the possibility of open storage using a box of your own construction, and a liner custom made to fit from American Solartechnics? He also does heat exchangers for that kind of setup. And DHW.

 

[Newfiestang]

You might want to run this stuff past your insurance guy. The only thing mine told me is as long as the boiler has a CSA sticker you're good. $3k might not be so bad to step up to a Froling.

Did you check out the possibility of open storage using a box of your own construction, and a liner custom made to fit from American Solartechnics? He also does heat exchangers for that kind of setup. And DHW.

Yes for sure, waiting to hear back from them but think i already know the answer, like needed.

I havent explored a DIY box but even if I did go that route the cost of liners (apparently need two), exchangers (2 min, but likely 3), then $ exchange, freight, etc i still dont think there would be much savings, based on 500 gallons. The liners are $1.25 per ft, exchangers range from $695 - 950, all in US$ of course.

On top of all that I would still have to likely get this past insurance, not sure how they would feel about a 500+ gal water tank stored in the basement. Further to that I dont see how a unpressurized tank system is as efficient but maybe its a minuscule difference. Then there is the issue some have with treating the water in the tank when its left for the off season.

Having said all this, what are some guys building these out of?