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Floor heat boiler selection

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Dragster Racer

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Feb 9, 2008
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Location
Morrison, IL
Looking for good value and correct selection of a boiler/water heater for floor heat. Heating about 1400 sq ft of well insulated basement that only needs a few degrees of extra heat, and a garage that we will only keep at 40 degrees or so.
We are in northern Illinois and there is regular pex non ox barrier tubing in the floors.

The calculators I have seen look like 60k btu would be enough. But what do I need to know about a non ox barrier tubing installation?
 
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78SC4X4

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Apr 21, 2018
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370
Location
Port Orchard Wa
Your tubing will allow oxygen to pass through the tubing wall. Rust is oxidated iron. So it will raise havoc with cast iron boiler. So choose a non-cast iron boiler and install the appropriate air eliminator in your system. Do your homework. There's lots of opinions on how to set up your system.............
 
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George-in-NH

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Oct 27, 2016
Messages
23
I'm trying to decide on a LP Boiler for my 28x32x12 radiant slab garage as well - What I've found is that small mod/con boilers aren't that popular!

I'm a DIY'er and here's where my designs have led:

Navien NHB-055 - Great looking small unit that I can't buy anywhere since I'm not licensed (... I learned too late).

Bosch ZBR-16-3 - Again looks to fit the bill. I ordered it from Supplyhouse, after 2 weeks they cancelled my order - it is discontinued.

Triangle Tube CC50S Challenger - Same deal, tried to order and its discontinued. Another 2 weeks colder here, doh!

I'm now thinking of a Weil-McLain Aquabalance AB80-H. I'm checking availability before I consider designing around it again. It is too big but has a 10:1 Turn Down Ratio so its low modulation output is less than above. There's no data for output with LP vs NG - I'm waiting for a response from WM.

Anyway - I added this to this post as I thought it was relevant. I'm going to do an original post on my system when I have a design done. I've got a lot of info from this site during my garage build, so hopefully a full write-up of what I do will someday help some one.

Happy New Year,
George
 
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finn

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Location
The UP, God's country
My installer handles IBC boilers, made in Alberta, BC.

I have two of the combi units, one in the shop and one in the house.

Mine are both combi, but that’s because the combi option wasn’t much of an upcharge, and I will eventually get rid of the separate water heater.

Turn down ratio is about 8:1.
 
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whatuusay1

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Jun 15, 2009
Messages
106
You can purchase the navien from https://gadgetsgo.com. Navien wont support it though, but you'll probably find that to be the case regardless of the manufacture if you are installing it yourself. The only DIY friendly options I've seen are via box stores like Menards (which are just rebranded Takagi units). That said I've had good luck with Takagi tankless water heaters for use as cheap radiant heat sources, they lack the outdoor reset and probably wont last as long as some of the more expensive options, but they are rated for heat use (and piping options in the manual). I personally went DIY and navien (NHB-80) for my basement and garage and its been great. Make sure to pay attention to piping design guidelines for whatever boiler you go with (and avoid going too big).

Here's a design a friend of mine put together with a Takagi for his shop - https://www.dropbox.com/s/ix9s0uslk01kmt2/Radiant Design w Electrical.pdf?dl=0
 
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7

75gmck25

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Jul 21, 2014
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Location
Alexandria, VA
Once you find a few good candidates, verify how far your installer will have to go to get repair parts, and ask them how many repairmen they have that work on boilers. I live just outside DC, and gas boilers are no longer being installed in new homes in this area. That means there is not much demand for repair parts and not many companies that do the work.

When I needed a new Honeywell controller board for a Buderus boiler I found that the farthest south parts warehouse was in Binghamton, NY, and they would only sell the parts to an HVAC repair company. It took a few days to find a local HVAC shop that really knew enough about boilers so that they could get and install the parts I needed.

Bruce
 
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whatuusay1

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Jun 15, 2009
Messages
106
75gmck25 said:
Once you find a few good candidates, verify how far your installer will have to go to get repair parts, and ask them how many repairmen they have that work on boilers. I live just outside DC, and gas boilers are no longer being installed in new homes in this area. That means there is not much demand for repair parts and not many companies that do the work.

When I needed a new Honeywell controller board for a Buderus boiler I found that the farthest south parts warehouse was in Binghamton, NY, and they would only sell the parts to an HVAC repair company. It took a few days to find a local HVAC shop that really knew enough about boilers so that they could get and install the parts I needed.

Bruce
Click to expand...

Great advice too! I initially was looking at HTP and discovered that they were much less common than Navien. I still think HTP is probably a fine boiler and had features i couldnt get with Navien but decided I'd need support at somepoint and didnt want that headache. I also purchased quite a few sensors and what not for my unit so i can DIY the maintenance if its something small.
 
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George-in-NH

Member
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Oct 27, 2016
Messages
23
re whatuusay1 -

Thanks for the response. I've been looking at some specs and it looks like the small sizes of a boiler series might just be same/similar to the next size up. I.E. - The low fire min output is the same but the full fire is capped of on the "smaller" boiler. The outside dimensions are the same.

I had seen the gagetsgo selling the Navien NHB-055 but its not there now.

I realize that I'm probably giving up any shot at a warranty claim by installing DIY but I'll probably save more than the cost of a new boiler. Plus I'll know the system and be that much farther ahead if I have to fix it myself some day.

For those that may be inclined to give me a warning about blowing myself up - I am the type to do my research. Also, here in NH I can do my own work. I've already received a permit for the install and it will be inspected by the town.

I think I am going to go with a Weil-McLain AB80-H. I've confirmed that after conversion to LP the low fire will still be about 8000 Btu/hr so that is lower than any of the other boilers I've looked at.

I will be starting a new thread of my install so as not to further hijack this one.

Thx
 
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D

Dragster Racer

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Feb 9, 2008
Messages
1,891
Location
Morrison, IL
whatuusay1 said:
You can purchase the navien from https://gadgetsgo.com. Navien wont support it though, but you'll probably find that to be the case regardless of the manufacture if you are installing it yourself. The only DIY friendly options I've seen are via box stores like Menards (which are just rebranded Takagi units). That said I've had good luck with Takagi tankless water heaters for use as cheap radiant heat sources, they lack the outdoor reset and probably wont last as long as some of the more expensive options, but they are rated for heat use (and piping options in the manual). I personally went DIY and navien (NHB-80) for my basement and garage and its been great. Make sure to pay attention to piping design guidelines for whatever boiler you go with (and avoid going too big). For a small building like you've got I might suggest the Takagi H3M-DV (if you aren't wanting to spend 2K+).

Here's a design a friend of mine put together with a Takagi for his shop - https://www.dropbox.com/s/ix9s0uslk01kmt2/Radiant Design w Electrical.pdf?dl=0
Click to expand...


Slick design. If I was going two zones, one for garage and one for basement, just put the second zone parallel to the first?
Any good design resources? And reasonable sources for parts?
 
B

BBE

Member
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Jan 11, 2021
Messages
8
Location
MI - Michigan
We like raypak boilers personally. Have had good luck with them. But then again they are made fairly local for us too though
 
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whatuusay1

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Jun 15, 2009
Messages
106
Dragster Racer said:
Slick design. If I was going two zones, one for garage and one for basement, just put the second zone parallel to the first?
Any good design resources? And reasonable sources for parts?
Click to expand...

Hey sorry for the delay in reply, you could do it either with 2 zone valves and 1 pump, or 2 pumps. I did zone valves and 1 pump to save on electrical pump wattage over time but 2 ecm pumps don’t really use that much electricity. If you are running multiple zones you would probably benefit from plumbing your boiler in a Primary/secondary design. I’d confirm with your boiler manufacture for recommended piping (it’ll likely have recommendations In the manual). I ordered most of my piping and pieces from pexuniverse.com or supplyhouse.com. Here’s a design with 2 zones and an indirect water heater.

https://www.dropbox.com/s/0jjumlqp97m6i7c/Radiant Design.pdf?dl=0

Feel free to PM me for additional info/questions.
 
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D

Dragster Racer

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Messages
1,891
Location
Morrison, IL
whatuusay1 said:
Hey sorry for the delay in reply, you could do it either with 2 zone valves and 1 pump, or 2 pumps. I did zone valves and 1 pump to save on electrical pump wattage over time but 2 ecm pumps don’t really use that much electricity. If you are running multiple zones you would probably benefit from plumbing your boiler in a Primary/secondary design. I’d confirm with your boiler manufacture for recommended piping (it’ll likely have recommendations In the manual). I ordered most of my piping and pieces from pexuniverse.com or supplyhouse.com. Here’s a design with 2 zones and an indirect water heater.

https://www.dropbox.com/s/0jjumlqp97m6i7c/Radiant Design.pdf?dl=0

Feel free to PM me for additional info/questions.
Click to expand...

PM'in you
 
OP
D

Dragster Racer

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Messages
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Morrison, IL
Well I can't seem to figure out how to message. LOL. I used to know how.
With the garage tubes coming in almost up at the rafters, there is no chance that I can see to get the tank and air separator above those tubes. Is that a disaster? I'm sure I couldn't get the tank up there.
Any trick in selecting a pump? Your diagram is very helpful.
 
L

lockhart3

Member
Joined
Dec 22, 2019
Messages
17
Location
Idaho
Dragster Racer said:
Looking for good value and correct selection of a boiler/water heater for floor heat. Heating about 1400 sq ft of well insulated basement that only needs a few degrees of extra heat, and a garage that we will only keep at 40 degrees or so.
We are in northern Illinois and there is regular pex non ox barrier tubing in the floors.

The calculators I have seen look like 60k btu would be enough. But what do I need to know about a non ox barrier tubing installation?
Click to expand...


As far as the non ox barrier - be sure that you use only non ferrous piping and components. No steel only copper, brass, bronze, stainless steel.

Basically treat the system as if it was a potable water plumbing system. This will prevent oxygen entrained water from corroding the piping etc.


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L

lockhart3

Member
Joined
Dec 22, 2019
Messages
17
Location
Idaho
Pump sizing is easy, once boiler decision is made. Then need to know how the Pex is laid out. And distances and piping layout. Sketch that our and could assist you as needed in pump sizing.

Keep the loops close to same lengths to avoid requiring balancing, and keep lengths at 200 ft max if possible, or even 250 if must (this assuming 1/2” pex).

For the small loads you will have suggest finding a small fire tube versus water tube if possible. They handle the low flow low firing rate better.


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L

lockhart3

Member
Joined
Dec 22, 2019
Messages
17
Location
Idaho
LAARS mascot nice choice, they have very good install manuals that will help you with piping needs and venting etc. follow the manual for best results!

I don’t think you can find a boiler with low enough firing mode for small heat lo adds like you’ll have. All you can do is make sure boiler controls have anti cycling option ( LAARS does) and set the differential for temp on/off high like 20-30F. This will help limit cycling some. Only other good option on small systems is to add buffer tank, but that is costly and takes space.


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lockhart3

Member
Joined
Dec 22, 2019
Messages
17
Location
Idaho
Not at all an issue.

It would be a Closed loop hydronic loop, They s/b filled/pressurized to have ~5 psi minimum at high point and systems get purged of air on fill set up.

Then have an air separator/removal device in line after heat source at pump suction.


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