best boiler for radiant floor

[thejudges69]

I'm looking to get my boiler for my shop, hopefully before winter. What I have is a 40x100, 16 foot ceilings, r-19 insulated walls, r-38 insulated ceiling, foundation has 2 inches of foam insulation going down 2 feet all the way around, including the door openings, my roll up doors are 14x14 insulated at r-19, my floor has 1/4" high load vapor barrier, insulation under it. I'm looking for the best boiler option. Everyone is trying to talk me into a hot water tank which I think is a bad idea. I did however find a couple of industrial hot water tanks online that a supposedly specifically made for radiant floors. I have not got into researching them yet. I'd like to have a wall mount boiler so that its on the wall and out of the way. Does anyone have any suggestions? I have 2 manifolds, one with 7 loops and the other with 8, all 1/2" pert pex. I have propane for a fuel also. thanks in advance.

 

[bikesandcars]

Have you looked at these?

http://www.weil-mclain.com/products/residential-boilers

The Eco and WM97 have stainless heat exchangers. Glycol doesn't work with aluminum from what I've seen

The on demand boilers are heavier and have less head loss and greater efficiency.

I'm looking myself.

If I did a water heater I'd probably use a taco x block

If you are handy on a computer try loopcad and model your building for heat loss

Sent from my XT1585 using Tapatalk

 

[Jackfre]

Lochinvar, Veissmann, IBC, NTI, Weil, Navien, Rinnai, Buderus (Bosch) and others, but that will get you started. Al is ok with Glycol, but all of these manuf specify what they want in a glycol.

 

[thejudges69]

I really thought I'd get more feedback on this thread.

 

[Radix2]

I really thought I'd get more feedback on this thread.

You didn't give much info on what you expect or what constraints you have.

1. For radiant floors, the highest efficiency will be a condensing boiler. Simple exhaust, simple to protect floors from high temps- the only downside is cost.
2. Zones? Use plan?
3. Run one of the BTU calculators to estimate what you need as far as size.
4. Std residential HWH probably don't produce enough for your size. They also are prone to condense and rust out unless you add components or buy expensive commercial units that get you back toward a proper radiant boiler cost wise.
5. Brand names are like always - different people like different ones. I have triangle tube Solo nice unit.

 

[finn]

Get something that has a local parts ands service source, unless you're ok with waiting for parts to be shipped and doing your own diagnosis and repairs.

Lots of HVAC techs and service companies don't want to work on something they don't have training on.

 

[lowrider2]

I have the same set up as OP except only 2K SF and I'm considering using an 80 gal GE heat pump WH. I have 7 loops 300' each. No propane at the moment and never natural gas. Electric is 7 cents/KW. COOP has them on sale for $1080 with an immediate $500 rebate plus tax credit.

Any thoughts?

 

[Radix2]

I have the same set up as OP except only 2K SF and I'm considering using an 80 gal GE heat pump WH. I have 7 loops 300' each. No propane at the moment and never natural gas. Electric is 7 cents/KW. COOP has them on sale for $1080 with an immediate $500 rebate plus tax credit.

Any thoughts?

Does it produce enough btus for your place - what is the requirement?

I question the logic of using a heat pump inside your building for radiant heating - the heat pump is efficient because it moves heat from the air around it into the water. Makes great sense in a warm climate where you are running air conditioning...but in a heating system you are just moving the heat from the room into the water to heat the room .....I don't see any efficiency advantage over just using a resistance heater ( which is 100% efficient in this usage already) - the nature of radiant heat defeats the heat pump if you are not using a different source of warm air.

So I would just get an electric boiler or heater which will save money,be simpler and be as efficient.

 

[Firebrick43]

I have the same set up as OP except only 2K SF and I'm considering using an 80 gal GE heat pump WH. I have 7 loops 300' each. No propane at the moment and never natural gas. Electric is 7 cents/KW. COOP has them on sale for $1080 with an immediate $500 rebate plus tax credit.

Any thoughts?

Radix2 beat around the bush but is right.

A big fat no! What your proposing is a perpetual energy scheme and it does not work.

Now don't think I am knocking HP HWH. I have a GE in my house and is wonderful. But it cools and dehumidifies in the summer and since the house is heated with wood mostly what it steals in the winter is ok. But if it was stealing heat from the place it's heating. That does not work. And being in Idaho there is not a place you can put it to steal heat from that maintains 40+ degrees through the winter.

What is your cost per kW there? I know here at 14 cent electric heat is a big no unless it's geothermal heat pump but install cost is very high. I think propane would have to be 3.50+ to make electric resistance heat/traditional air source heat pump look attractive here. Buy you own tank and have it summer filled only and your cost is usually at or under a $1 a gallon for propane.

 

[lowrider2]

I just filled my 1K gal propane tank at a different shop and it was $1.65/gallon. Our electric is $0.07/KW so it's pretty cheap. So, a high efficiency resistance hot water heater would be the best?

I have a Tagaki on demand propane in my other shop and it has had 3 service calls in 5 years...sensors mostly I think but one service call was over $300. It now won't fire up all the time unless I unplug and turn off the propane...wait 5 minutes then re-start. Resistance 60 gal HW seems like the simplest way to go....pretty much plug and play I think.

 

[Firebrick43]

Your prices are fairly close for electricity vs propane. 2.05 for 100k btu for electric and 2.18 for 100k buts propane with 82% efficient water heater. Of course propane is usually cheaper than that summer fill if you have enough storage. It would be hard either way to so one is better than the other. Something like a rheem marathon with a fiberglass tank or a HTP/Westinghouse with stainless tank is going to be much more durable and not rust out. Make sure you do a heat loss calc. If the first hour rating of the hwh -25% doesn't cover the heat loss it won't work

 

[rburke65]

Thejudges69.......are you.umbing this up or using a heating contractor and if so who? I'm in the Youngstown area also and looking. Thanks.

 

[theoldwizard1]

No brand recommendation, but make sure it is a CONDENSING boiler. They are more efficient.

 

[lowrider2]

Your prices are fairly close for electricity vs propane. 2.05 for 100k btu for electric and 2.18 for 100k buts propane with 82% efficient water heater. Of course propane is usually cheaper than that summer fill if you have enough storage. It would be hard either way to so one is better than the other. Something like a rheem marathon with a fiberglass tank or a HTP/Westinghouse with stainless tank is going to be much more durable and not rust out. Make sure you do a heat loss calc. If the first hour rating of the hwh -25% doesn't cover the heat loss it won't work

Heat loss appears to be 5040 BTU. The 80 gal 5500 watt Westinghouse provides 89 gal/hr 1st hr. at max 180F and 23 gal at 100F rise/hr.

From there I'm lost. It would seem that water temp would have a large bearing on how fast the system would make up heat loss. I'm thinking of running 140F or maybe lower.

Now what?????

 

[Firebrick43]

Something is wrong with your heat loss calc. How well is it insulated? A good sanity check, but not a replacement for a proper manual j is 15-25 btu a sqft for a great structure to 45+btu per sqft for a drafty one. At 2000 square ft you should be well north of 40 to 60 k btu per hour maybe much higher depending on insulation, ceiling height and how warm you are going to keep it.

5500 watt hwh is 18700 btu so no dice on the electric tank heater unless you run several together.

 

[lowrider2]

Just didn't hit the zero enough times. 50,400 sound better.

Still won't work with a water heater eh!

 

[chew]

Something is wrong with your heat loss calc. How well is it insulated? A good sanity check, but not a replacement for a proper manual j is 15-25 btu a sqft for a great structure to 45+btu per sqft for a drafty one. At 2000 square ft you should be well north of 40 to 60 k btu per hour maybe much higher depending on insulation, ceiling height and how warm you are going to keep it.

5500 watt hwh is 18700 btu so no dice on the electric tank heater unless you run several together.

You can Dual feed the HWT and wire both element separately so they come on together and don't flip flop. Gives you 37400 btu. If you need any more go with a proper electric boiler.

 

[lowrider2]

Propane is looking better but then I need a permit and engineer designed system. That's one of the reasons I wanted to use electric HW.

 

[thejudges69]

Ok, I didn't get any emails from the last 4-6 replies as usual with this forum.

Anyways, back to my issue.

How do I do a heat loss calculation for my shop? I am using my shop for maintenance on my truck and trailer, anywhere from a few hours a day to a few days a week to a few weeks a month. It's really hard to regulate how much time will be spent in it, but I want it comfortable when I do use it.

The shop is 40x100 steel building, the side walls are 15' high and roughly 16.5' to the peak, it's an open floor plan, the walls have r-19 insulation, ceiling has r-38, no windows or skylights, 2 14'x14' doors r-19 insulation in them, each door has 4 windows that are insulated but I don't know the rating on them. The man doors, I don't know that they are insulated, but 2 36"x80" man doors. The floor is 6-7" thick with ¼" high load insulation under it with a vapor barrier on both sides, this has a very low insulation factor I think r-3 maybe, the foundation is concrete cinder blocks, I have 2" foam insulation going down 2' below grade. I have 2 4'x4' squares with no insulation or moisture barrier under it, that's where my 2 post lift will sit.

I was in my shop the other day and it was closed up for several days. The temp was 26-27 degrees outside and the building was 50-55 inside. Very comfortable but I still don't know how to do a heat loss calculation. I was told that I needed a 100k BTU boiler.

I'm again heating with propane, I have 2 manifolds, 1 have 7 loops and the other has 8 loops, all ½" tubing 270-300 foot long. I don't plan to zone the building. I have no plans at this time to partition anything or not heat anything, so I'm going to run 1 zone for now. Who knows what the future will bring.

I got a recommendation for a condensing boiler as stated above. For some of the reasons stated above, simple to exhaust, can work at lower BTUs and they can hang on the Wall and be out of the way.

I have researched some of the boilers listed above. I have a buderus in my house with oil heat, great unit but I am looking at a few others. The HTP boilers I read not much good about on line, Lochinvar is the same, I read very little good about online and also have had a couple installers tell me the don't prefer to work on them for lack of parts and apparently they are constantly changing designs. I have not checked onto Weil yet or a lot of the others listed above. I also talked to radiantec which is posted on the garage journal home page, I'm not finding much good about the American HWH they offer, they claim it's for radiant floors but I'm not 100% on that.

I'm really wanting to purchase and do this install myself with a family friends help who is a retired commercial plumber/heating installer.

 

[thejudges69]

 

[BadgerBoilerMN]

The key term here is Water Heater. You will wish you had a properly sized boiler...

 

[BadgerBoilerMN]

A propane condensing boiler is an excellent choice. The best one depends on your heat load. Sadly most heating contractors don't know how to do a heat load. Some vendors will do it for you. You wouldn't buy a tractor without knowing what you were going to pull.

I have installed most of the condensing boilers and have an HTP-Eft-LP waiting in the shop for me now and an NTI-Tft-NG doing snow/ice melting at another place. Both are excellent boilers. Factory training makes choosing and servicing much easier. You will have to service any propane condensing boiler regularly.

It sounds as if you have a insulating "blanket" under the slab. It is not really insulation but not the end of the world. More reason to do a Manual J before you choose the proper size boiler. Local parts and service is reassuring.

I keep my shop at 50 most of the time and 60F when doing light work. A WiFi thermostat allows me to monitor the temp in case I lose heat and enables remote control so I can call ahead a boost or lower the temp if I forget. Overnight is all it takes in most weather.

We no longer use Al heat exchangers and propylene glycol costs more to pump and to heat so a minimum mix is in order. Never, ever, use automotive anti-freeze for heat transfer.

Never use 'water heaters' as space heating appliances. You have to be a lot smarter to cheat and get away with it.