heating question

[caper150]

Yes it's getting close to that time of year where the discusssion changes from how we cool our garages to how are we heating them. What I am trying to figure out now is what I need to hook up to my in-floor heat system for my shop and how many BTU's it takes to heat a shop of my size 1280 sq. ft. I was orginally told that a 40 gal. hot water heater would be sufficent, and quickly found out last year that isn't the case and cost me a fortune to heat the place. Any suggestions?? will a larger hot water heater be enough, a micro boiler?? gas or electric?? I need some help here guys,point me in the right direction.

 

[HoosierBuddy]

I'll start at the last part and move backwards.

You need to decide what fuel you want to use. You have to base that first on availability and second on cost. Availability varies widely and cost varies somewhat too, but for me it would work out like this:

Natural Gas $9 per Million BTU
Electric Power $30 per Million BTU (10.2 cents per KWH)
LPG $16 per Million BTU

If your costs are similar, your fuel choice should jump to the top. In almost every case, it's going to be a cheaper easier install to go with electric. But in the end, it'll cost you a lot more money.

Once it's clear you want to go gas, you can look at efficiencies of various equipment that can heat your water. They are going to break down somewhat like this (depending on equipment choice!):

Tank style water heater .80 (NEGLECTING TANK LOSSES)
Tankless water heater .90
standard gas boiler .80
Tankless boiler .92

So...pretty quickly I'd be looking at a tankless boiler or tankless water heater.

From there, I'd be talking to the manufactuers about what their unit is designed to do. Obviously a tankless boiler will heat water for space heating, but if you go the tankless water heater route (cheaper) make sure the manufacturer is in agreement that their unit will work for you.

When faced with the same choice, I went with a tankless boiler. It was more money, but it was designed for the job. 4 years later, it still works great. If you get a modulating boiler, it will throttle based on the load, which makes it a great choice where the total BTU requirement may be a little fuzzy.

In your situation, based on what you've told us, I have no idea how many BTU's/hour you actually need. Insualation and outside temperatures will have a lot to say about that. If you're in MN though, it'll be a substantial amount. Trinity Ti 150 from NY Thermal for mine. I'm in a slightly warmer climate, but I have more sf than you. I'm sure it'd work, but you might get by with something smaller/cheaper too.

Good Luck!

Phil

 

[caper150]

The shop is 32X40 with 10' high walls r13 in the walls and 15" of blown in cellouse in the ceiling, temps here run anywhere from the mid 30's to -30's in Jan. Feb. I'm not looking to work in 80* temps 60-70 would be nice maybe.

 

[jkorby]

what type of tank-less boiler would you recommend on a 1000 sf poll barn? I have just had the concrete laid and the 1/2 pex tube is sticking out of the floor....what should I do?

 

[D.J.]

Is it 1 1/2" pex or just 1/2" pex tubing, 1 1/2" sounds a bit oversized to me?
________
Wellbutrin lawsuits

 

[jkorby]

yes its 1/2 inch pex

 

[jvitez]

Here in Manitoba a good rule of thumb is to use 10 watt/ ft2 of electric heat for residential construction. For a very well insulated space 7 watts/ft2 will do. I had 9 W/ft2 in my old garage which was only intermittently heated forced air electric, and it would warm up in about 90 min to a comfortable temp in the coldest winter days. I had only R12 walls, R40 ceiling, and an insulated garage door. BTU/W conversion is 3.413.

But you should really do a proper heat loss calculation before spending any more money.

A bigger heater won't save you money. Btu is Btu. If you need X amount to keep your place warm, it doesn't matter how it's delivered as long as you get the Btu. What you need is to get a proper heat loss number, then find the most efficient heater that can provide that amount at the minimum. A standard water heater can heat your garage just fine if it has enough input capacity. Just not very efficiently.

 

[nate379]

Best bet would be to go down to the local plumbing/heating store that sells boilers and talk to those guys.

#1 you want something sized right.

#2 you want something you can get parts for... locally

#3 you want something that is common to your area in case it breaks and someone has to work on it.


I don't see how a water heater can even work well. I heat my house and garage, about 2100 sq ft total with a 90,000 BTU boiler. In the dead of winter it is darn near running non-stop. R-21 in the walls, R40 ceiling, R10 floor.

Yes you can get a water heater near that BTU #, but it would be a commericial unit, probably costing more than a boiler.

 

[Sparks4184]

Here's a gas or propane solution that works really well and for what I think is a pretty good price. They're called Hot Dawg heaters by an outfit called Moline.
http://www.shophmac.com/heaters/gas-heaters/gas-unit-heaters.html?attribute_hmac_brand=730 They were designed for use in shops/garages and heat quite efficiently. You won't be smokin' but pretty comfortable if you've got reasonable insulation in cold climates.

My second suggestion is a pellet stove. That works well for my garage, about 700 SF just south of San Francisco. It gets chilly here in the winter (and summer) not usually below 45 at night and rarely below 40. I only use it when I'm actually working in the shop and it costs about $5 in pellets/day to stay comfortable without a jacket.
Mark

 

[nate379]

Depends on location. Heating with pellets here is one of the most expensive ways to heat, electric and propane being a bit higher. (Electric is ~$0.15 Kw/hr and propane is $4/gal)

Nat gas is actually the cheapest. Wood is even a bit more expensive if you have to buy the wood. I have a woodstove as backup heat in cause gas or electric would go out. And of course having a nice fire going in the stove when it's -30* is awesome.

I don't know what you keep your garage at, but I find 55-60 plenty comfortable to work at with a T Shirt. If I keep the doors closed the garage heat rarely kicks on even since the boiler and water heater are in there and give off some heat.

 

[caper150]

well I found this heat BTU calculator and after filling in the boxes it said that 27200 BTU's is what is needed to heat my shop, seems kinds low to me, I did have a guy here one time who was fixing my house furnace and I thought he told me I would need around 90000 to heat it. I told him to get me a price on something that would work and never heard from him again, guess he was too busy.
http://www.heater-store.com/heater_calculator_info.htm

 

[nate379]

I just put in a 30x40 building with 10 ft ceiling and it says 117,000.

I don't know what your temps get down to, but I figured -20 and keeping the garage at 70*, so that is a 90* temp difference.

 

[HoosierBuddy]

http://www.nythermal.com/trinity_ti

If you look at that page at the smallest boiler they sell, it modulates from 14,000 to 95,000 BTU output based on the water temperature coming back from your loop.

I feel it would work great for your application. That being said, you need all the other components in your radiant system to be correct too. I've never heard of anyone using 1 1/2" PEX for radiant. You need to talk to someone that has done some of these systems, even if it's just an internet supplier of radiant heat products (do a search for hydronic heating and you'll find several) to see what you need. Certainly though you'll need manifolding, zone pump(s), thermostat(s), expansion tank, etc. to make this work. Even if you buy the boiler I've recommended, it's just step 1 to getting your system working.

Now...backing up a little...

What exactly do you have in your slab now?

Does it have polystyrene underneath it?

Phil

 

[jkorby]

I used 1 1/2 INCH pink Styrofoam, 4 inches create, wire mesh on the inside and fiberglass on the outside apron and lean-to off the back. I am in the process of getting the electric run to the building, I am going to make it all electric. I have been reading a lot on here and it looks like propane might be a good option as well. I have room on the side to put in a tank but it is across the room from where my PEX is coming out of the floor. Just got the two garage doors hung this weekend! I will get some pics up to night.

 

[jkorby]

ok can I post pics right to here or do they need to be hosted?

 

[jkorby]

Your right not sure what I was thinking, its 1/2 inch pex. Yea 1 1/2 would be a lot of water!

http://www.nythermal.com/trinity_ti

If you look at that page at the smallest boiler they sell, it modulates from 14,000 to 95,000 BTU output based on the water temperature coming back from your loop.

I feel it would work great for your application. That being said, you need all the other components in your radiant system to be correct too. I've never heard of anyone using 1 1/2" PEX for radiant. You need to talk to someone that has done some of these systems, even if it's just an internet supplier of radiant heat products (do a search for hydronic heating and you'll find several) to see what you need. Certainly though you'll need manifolding, zone pump(s), thermostat(s), expansion tank, etc. to make this work. Even if you buy the boiler I've recommended, it's just step 1 to getting your system working.

Now...backing up a little...

What exactly do you have in your slab now?

Does it have polystyrene underneath it?

Phil