New Boiler Design / Any help appreciated

kbisnett

Hello HeatingHelp Community!

Newbie here so go easy! :-) Always been a big DIY individual and installed my last HVAC (Rheem 96% two-stage furnace and 16 SEER 2.5 ton A/C unit) which was a blast to do and learned a lot. We recently purchased a new home and it's in need a boiler system... badly...!

The current unit is well over 20 years old, but it is a Weil McClain 81% efficiency. Can't tell the size or anything of that sort due to the info being rubbed off from age - I do have a serial number. It consumes propane like crazy (almost 1500 gallons so far in Upstate NY) and it never starts correctly. I've cleaned all the sensors and tubes, additionally calling in professional help and it will only fire half the burners at times or just not fire at all and sit there running for 10+ minutes.

So with all the being said, I'm looking to move to a condensing boiler. I've looked at US Boiler K2s, Lochinvar WHB series, and Naviens. I'm not set on what type of boiler yet. We have 2 zones + an indirect zone. Right now they are all valved, I plan to switch over to circ pumps for each zone and I'd like to use a Caleffi Hydro Seperator instead of the P/S loop. Total baseboards through the house is 157 ft almost evenly divided between both zones (Upstairs + Downstairs). Roughly 80 ft downstairs and the rest upstairs. Indirect is a 40 GA tank, but I'd like to move up to a 50Ga tank during replacement and get that all squared away as well.

Had a company come in and quote a 155 BTU which seems awfully high - I need to perform a manual calc, they didn't even bother to do one. House was built in 1998 and most of it has the ZIP system with 2x6 insulation.

So I guess a few questions: Any brands that you recommend? Does the 155 BTU sound high for the amount of baseboards that we have? Anyone done this with a Hydra Seperator and 3 zones that can share a picture of the work? I guess I am trying to figure out all the piping in my head - we have a large wall that this will be placed on so I want to make it look extremely neat. Will attach some photos of the current setup.

Paul Pollets

If you have 157 ft. of copper fin tube, you have a load of 83K BTU's. Using a mod-con boiler assumes the radiation installed can heat the home when at much lower design temps or the the boiler will stay on high fire, and not modulate below condensing temperatures (140), which reduces it's efficiency. A room x room heatloss would show the requirements and if the existing baseboard can heat the home at 140. If so, a mod-con is a good choice. If not, a cast iron appliance may be a better choice.

Jamie Hall

As @Paul Pollets implies, the first step -- before you even begin to think about what boiler you might like -- is a room by room heat loss. This will give you two things: how big a boiler you really need, and, perhaps more important, what temperature you need to run the radiation at to heat the spaces.

Once you get that information you can begin to think about the kind of boiler and zoning and piping and all. But not until then.

kbisnett

Thanks folks! Really appreciate the comments!

Do you have a preferred tool to do the load or heat loss calc that I can plug all the numbers into? I'll run one tonight and would love any advice you may have.

kbisnett

Hi Folks!

@Jamie Hall @Paul Pollets - I ran a Heat Calc using Slant/Fin App. (photo attached) It looks like a pumped out a total of 38226. Also, attached a picture of my (sad) current boiler.

EBEBRATT-Ed

Well I guess now you know what to think of the 150,000 btu boiler quote.

How many square feet of living space?

Double check your numbers. I am not doubting them but it does seem strange they would install double the baseboard footage needed.

What size pipe did they use on your two heating loops 3/4" or 1"?

Is some of your baseboard just bare pipe with no fins or are all 150 feet finned?

kbisnett

EBEBRATT-Ed said:

Well I guess now you know what to think of the 150,000 btu boiler quote.

How many square feet of living space?

Double check your numbers. I am not doubting them but it does seem strange they would install double the baseboard footage needed.

What size pipe did they use on your two heating loops 3/4" or 1"?

Is some of your baseboard just bare pipe with no fins or are all 150 feet finned?

Unbelievable at such a high amount! One company wanted to put in a 199K! :-O

So - I measured for square footage and we are sitting at right around 3300 sq. ft. finished not including the basement. I ran through all of the baseboards again and came up with the same amount of total baseboard footage. All baseboards are finned except for when it makes a corner. We have baseboards galore! lol.... Looks like manifold is 1" and the runs are 3/4.

Half of the basement is finished as a workout room but no zones from the boiler. We've talked about adding a few loops for the garage and walk out basement, but it has electric baseboard, which we rarely use. Would love to ensure we size the boiler properly to take that into account.

Jamie Hall

With the amount of baseboard you have in relation to the actual heating load (you did use the correct options for insulation and so on? Just checking...) you certainly have the opportunity to make good use of a mod/con boiler -- but not if it is much too big. To get the best results from a mod/con, it needs to be accurately sized to the heat loss.

The company that quoted 155K and didn't do a heat loss is not one to do business with; see if you can find one which will do the heat loss first -- and then compare their numbers to yours.

Brewbeer

150 feet of baseboard putting out 260 btu/ft will meet your calculated design load of 39,000. How hot the water needs to be to get this out put is based on the baseboard manufacturers ratings. Can you ID the make and model of the baseboard?

sallaberry

Isn’t baseboard 500 btus per foot? So 78,500 btus are needed plus storage tank? Both navien or locknivar tankless would be great units if the system requires a recirc system.

STEAM DOCTOR

> @sallaberry said:
> Isn’t baseboard 500 btus per foot? So 78,500 btus are needed plus storage tank? Both navien or locknivar tankless would be great units if the system requires a recirc system.

Depends on water temp. And flow rate.

kbisnett

Jamie Hall said:

With the amount of baseboard you have in relation to the actual heating load (you did use the correct options for insulation and so on? Just checking...) you certainly have the opportunity to make good use of a mod/con boiler -- but not if it is much too big. To get the best results from a mod/con, it needs to be accurately sized to the heat loss.

The company that quoted 155K and didn't do a heat loss is not one to do business with; see if you can find one which will do the heat loss first -- and then compare their numbers to yours.

Couldn't agree more - so far I've had 4 companies give us a quote in Upstate NY and none have been willing to run a heat load calculation. All have been using condensing boilers in the quotes @ 155K and above. This is one of the projects that I will be learning as I go and do all of the work. I simply don't trust a company to do this right.

I used all the proper options from what I can see within the app. The house was built in 1998 but then renovated. All 2x6 construction with vapor barrier. Basement is fully insulated except in the boiler room and attic is extremely well insulated. I also just got done insulating the attic ladder with an R50 box and weather tight seal. Doors and Windows are all Anderson 400s, but they are only double pane which I selected in the app.

Brewbeer said:

150 feet of baseboard putting out 260 btu/ft will meet your calculated design load of 39,000. How hot the water needs to be to get this out put is based on the baseboard manufacturers ratings. Can you ID the make and model of the baseboard?

Great point - all of the baseboards in the house are Slant Fin Model 15-75E with the 3/4 element.
Based on the specs that I just looked at - at 4 GPM and 130F, I would be receiving 260 BTUs. Does that sound right?

sallaberry said:

Isn’t baseboard 500 btus per foot? So 78,500 btus are needed plus storage tank? Both navien or locknivar tankless would be great units if the system requires a recirc system.

I was really interested in the Lockinvar boiler but after seeing the IBCs up close at a home trade show and some of the reviews, I think I may be sold on an IBC SL Series G3.

I guess the real question I have is how to properly size the boiler -

hot_rod

Looks like the IBC 10-85 would be a good match. The control has some nice features like heat appropriation which with ODR would be a sweet setup

Jamie Hall

Seems to me that you have done step 1 there -- you know what your heat load is (and it seems reasonable for a well insulated house). I've never known @hot_rod to steer someone wrong, and I agree that the IBC 10-85 looks like a good unit for your application.

It is not -- none of them are, really -- all that hard to install and get running right. It's mostly a matter of taking it slow and easy and thinking through each step -- and reading the directions. None of us like to do that, but sometimes it does help! The advantage is that having done it, you will know exactly how the system operates -- and is supposed to operate -- and you should be able to tweak it to make it really sing.

Brewbeer

Great point - all of the baseboards in the house are Slant Fin Model 15-75E with the 3/4 element.
Based on the specs that I just looked at - at 4 GPM and 130F, I would be receiving 260 BTUs. Does that sound right?

I would run this calc using 1 gpm, and don't forget that the baseboard manufacturer is including the magical 15% HEF, which is just a fancy way of stating that the values provided by the manufacturer overstate output by 15%. In other words, when the output table indicate 260 BTUs, it's really 221 BTUs.

But in any event, based on what you know and have provided, there is sufficient baseboard in your house that you would be well within condensing conditions for most of the heating season.

I'm also a big DIYer, and designed a low temp baseboard system for my house a few years ago. Check out the design thread in my signature.

hot_rod

If you go with a mod con, you really need to set them up with a combustion analyzer. Many boiler failures and lockouts are tied to improper burner adjustments. No way to guess at that critical step.

kbisnett

hot_rod said:

Looks like the IBC 10-85 would be a good match. The control has some nice features like heat appropriation which with ODR would be a sweet setup

Thanks! I was looking at the 85 and then I read somewhere that with an Indirect, sometimes they want the BTU to be over 100, which made me look at the 115K? If it's modulating, would it kill my propane savings and condensing by using a 115K? Or is this a myth and I would technically be fine with a 85?

Jamie Hall said:

Seems to me that you have done step 1 there -- you know what your heat load is (and it seems reasonable for a well insulated house). I've never known @hot_rod to steer someone wrong, and I agree that the IBC 10-85 looks like a good unit for your application.

It is not -- none of them are, really -- all that hard to install and get running right. It's mostly a matter of taking it slow and easy and thinking through each step -- and reading the directions. None of us like to do that, but sometimes it does help! The advantage is that having done it, you will know exactly how the system operates -- and is supposed to operate -- and you should be able to tweak it to make it really sing.

That's great to hear! I am an instruction manual crazy man. I'm an Azure Cloud/Data Center Engineer by day and I follow things to the tee - sometimes a bit too much OCD which is why I am thinking about the Hydraulic Separator instead of just closely spaced Ts. I'd rather over-engineer then under - as long as I am not starting to go too crazy with it... :-) I tell my customers all the time - I can build it for you, but once it's turned over you will not understand how it was built unless you build with me.

Brewbeer said:

Great point - all of the baseboards in the house are Slant Fin Model 15-75E with the 3/4 element.
Based on the specs that I just looked at - at 4 GPM and 130F, I would be receiving 260 BTUs. Does that sound right?

I would run this calc using 1 gpm, and don't forget that the baseboard manufacturer is including the magical 15% HEF, which is just a fancy way of stating that the values provided by the manufacturer overstate output by 15%. In other words, when the output table indicate 260 BTUs, it's really 221 BTUs.

But in any event, based on what you know and have provided, there is sufficient baseboard in your house that you would be well within condensing conditions for most of the heating season.

I'm also a big DIYer, and designed a low temp baseboard system for my house a few years ago. Check out the design thread in my signature.

Thanks Brewbeer! I was drooling over your design thread, I checked it out last night once I saw it in your signature. Really beautiful work and well piped!!

I ran the calc using the 1 gpm and it came out to be roughly 240 BTU at 130 degree temp, which would be 225 BTUs with the 15%. I'm surprised at how much baseboard I have in the house which makes me continue to rethink my heat load calc. It's a bit crazy. I also think our current boiler is at least 130-140 that is always on that BTU. Crazy to think about the amount of propane we are streaming through. Do you think with those numbers at 1 gpm, we are still good for condensing?

hot_rod said:

If you go with a mod con, you really need to set them up with a combustion analyzer. Many boiler failures and lockouts are tied to improper burner adjustments. No way to guess at that critical step.

Copy that loud and clear - would it make sense to buy a combustion analyzer? I know they look pricey at $300-400, but without paying for install - it may be worth the investment into one? Or would you recommend another way?

Also, I'm planning to spec out the system with all the parts - would love to have you all review and advise if I am missing something in my diagrams.

kbisnett

Hi Folks!

Read the IBC G3 manual and also reading some of the information on the Caleffi Hydro Sep4. Some diagrams do not align with the others.

With the IBCG3, I plan to use one side for the Indirect Water Tank, then the other side of our slant rads and two zones, along with the primary pump for the hydro.

IBC shows the cold water fill on the hot line - while Caleffi shows it on the return line after the Hydro closest to the boiler. Which is right and/or wrong? Maybe, not a binary answer?

One other question - any recommendations on Circ Pumps? I've been looking at the Taco007e for the Primary pump to the Hydro, then for the two zones (Upstairs/Downstairs) and also the indirect. It looks like you do not have speed control with them, they auto ramp up and down. Is this an OK application for what I am doing?

Thanks all! :-)

hot_rod

The lower drawing is my suggestion, but I prefer to have the expansion tank at that lower connection also, upstream of the pump

Air purger stays where it is shown

kbisnett

hot_rod said:

The lower drawing is my suggestion, but I prefer to have the expansion tank at that lower connection also, upstream of the pump



Air purger stays where it is shown

Thanks Hot Rod! So just to make sure I understand correctly. Circ should stay on return pumping into the boiler, however after circ have expansion tank and fill system. Would I want an air vent there still and also one on the hot loop?

EBEBRATT-Ed

@kbisnett

Most gas fired water heaters are around 40,000 btu inpt. Unless you have a huge domestic water load I would use a 50 gallon indirect and not upsize the boiler for DHW load. The 85,000 loks like the right size

If we are talking whirlpool tubs or something that could change things

hot_rod

The drawing shows a Caleffi Sep 4
I think😉
So no additional air purger would be needed

The expansion could be on any of the 4 ports, I prefer either bottom connection. Tank connection first, circulator after the tank, pumping away from the tank, towards the boiler, lower left connection is my advice

kbisnett

Hi Folks!

So I'm finishing putting together my parts list. Regarding Circulators - for Zone 1 (Downstairs), Zone 2 (Upstairs), Indirect Heating, and Primary loop for the SEP4 - I'm planning on purchasing 4 Grundfos Alpha2 15-55F. Any issues with all of the circs being this or do I need to go for a higher head circ on the primary loop? Maybe lower on the indirect?

So few questions:

Am I good for the same type for all zones?
What's the difference between a Rotating Flange vs. Standard Flange? Recommendation?
Guidance on isolation valves that I should use between the circs?

hot_rod

When you say primary loop, do you mean the boiler circulator? IBC should give you the sizing info for that circ, Alphas should be fine on the zones. Indirect probably fine with an Alpha unless it has a small diameter coil?

Standard flange is easier to get at bolts Really doesn't matter as you turn the iso flanges to match the pump flange.

Webstone seems to have the widest selection of iso flanges. On one side you can use the purge port style, on the other side just an iso flange to save some $$