Radiant Heating questions

[SprintCC]

Geting ready to build my garage, 30x44 with Radiant Floor Heat, vapor barrier, with 6 inch slab, and the building will be insulated

2 Questions:
1) I've gotten quotes from people, for the radiant heat some recommend a small hot water heater, others a small boiler (both electric). Each say's that the size I'm looking at (1320 sqr feet) is ideal for the heater type they are recommending . I'm outside Philly so it gets cold, but not that cold. Are they both right? Whats the tradeoff of one vs the other. I would like to have hot running water in the shop-sink.

2) One main advantage of Radiant heat from my understanding is there is not cirulated air (as in forced air), minimal moving air so you feel warmer and can set the thermostat lower . If I add an exhaust fan or a large air filter that moves the air around making air currents will these currents cause a problem with the radiant heat (ie make it feel like theres a draft, so you feel colder), or are the current too small to be a factor?

Thanks!
SprintCC

 

[Abodyracer]

Geting ready to build my garage, 30x44 with Radiant Floor Heat, vapor barrier, with 6 inch slab, and the building will be insulated

2 Questions:
1) I've gotten quotes from people, for the radiant heat some recommend a small hot water heater, others a small boiler (both electric). Each say's that the size I'm looking at (1320 sqr feet) is ideal for the heater type they are recommending . I'm outside Philly so it gets cold, but not that cold. Are they both right? Whats the tradeoff of one vs the other. I would like to have hot running water in the shop-sink.

2) One main advantage of Radiant heat from my understanding is there is not cirulated air (as in forced air), minimal moving air so you feel warmer and can set the thermostat lower . If I add an exhaust fan or a large air filter that moves the air around making air currents will these currents cause a problem with the radiant heat (ie make it feel like theres a draft, so you feel colder), or are the current too small to be a factor?

Thanks!
SprintCC

1) either one would work. I'm not to familiar with using the boiler setup when running potable water. A regular water heater would be fine for potable water though.

2) I've heard of people using ceiling fans to circulate air.

I'm sure someone more experienced will chime in with their thoughts.

 

[Charles (in GA)]

Your basic domestic electric water heater has two elements that range from 1.5kW to 6kW each- way short of 13.2kW. Most common are 4.5kW 220V elements..

Common household water heaters do indeed have two elements, (mine has two 5.5Kw elements), a lower and an upper. However, they are wired so that only one at a time is on. Normal use, the cold water enters the bottom of the heater thru the dip tube. as the lower part of the tank becomes cold, the thermostat kicks on the lower element. If you continue to use hot water and the lower element cannot keep up, the upper portion of the tank becomes cold and the upper thermostat switches out the lower element and turns on the upper element, so as to heat the upper most water in the tank, for "quick recovery". When you stop using hot water, the top warms up and the upper thermostat, being satisified, switches off the upper element and allows the lower element to be controlled by the lower thermostat, so the lower element comes on and heats up the remainder of the water.

Charles

 

[useless]

Sprint your garage is just a little bigger than mine. I'm at 1000 SQ FT. I have a 40 gallon gas hot water heater that can not keep up. I have it keeping the water warm 24/7 so it generally starts out in the 110 degree range when the thermastat calls for heat. I have 3 zones. The outside two are 2 runs of 800' and the center of the garage has 1 run of 400'. If I keep the valves partially closed to restrict the flow to the outer zones the water heater can barely keep up. It will run 3-4 hours steady before it's warm enough or the water heater has caught up. I would seriously look at a small efficent boiler, or a larger water heater than what I have. I'm thinking of going with a boiler before next winter myself.

 

[Kent in KC]

Check to see if your utility (gas or electric) has a deal on a 100 gal hot water heater. Mine does ($300) and a lower rate for using it.

 

[J Man]

has anyone used a tankless water heater?

 

[Vicious_Cycle]

has anyone used a tankless water heater?

Yep. 30x48 with 12'8" ceilings. 6" concrete floor. I used a Takagi TK-Jr gas water heater and 7 loops @ 200-250 ft each. It's clean and quiet to operate. Takes quite a while (day or two) to heat up.

I just finished my electrical work (well, 99% done anyway) and have not had the electric inspected yet, so I can't insulate yet. Thus, I don't run the heat full-time.

But I have run it enough to know that once the shop is insulated (R-30 ceiling and R-19 walls), this unit will have absolutely NO problem maintaining a nice temperature, regardless of the weather outside. I'm in NE Ohio, where we are looking at daytime highs around 8F this weekend.

Radiant systems by nature are much happier maintaining a temperature than they are cycling warm and cold.

 

[BowtieNut]

has anyone used a tankless water heater?

Same one here, Takagi TK-Jr gas, in a 28x48 with 10' ceilings. Walls are R19, ceiling R34-38, 4" concrete floor with 2" insulation under that. Mine is 6 zones of 250-300'. I've had it running a couple months now, and it seems to be working great. This weekend will really put it to the test though, it's supposed to be below zero (highs) for the entire next 4 days here in MN. So far I really like it (the heat, not the weather).

My neighbor has almost exactly the same setup & size, except he has a "Hydro-shark" electric tankless. He says he really likes the heat, but his electric bill for just the garage is always over $100/mo in the winter. I think he said it's closer to $150 for months like this. So far at a quick glance mine seems to be costing me about 25-35/mo, but I don't have a real good comparison yet. After a couple more months I'll really figure it out.

 

[SprintCC]

BowtieNut

This weekend will really put it to the test though, it's supposed to be below zero (highs) for the entire next 4 days here in MN.

How did your heating hold up?

Chris II
Blue Bell Pa

 

[PAToyota]

BowtieNut: What temperature are you running the garage? Are you keeping it constant or allowing it to "cool" somewhat when you aren't out there?

 

[kid]

just an FYI for comparision, my shop is 1060 square feet, 10' walls, half the shop has valted ceiling,5" slab, no insulation under slab but installed 2" foam board around the foundation from ground level down 2'. Using 3 300 ft. loops of 1/2" pex, & 1 40 gal. hot water tank with thermostat set at "warm". Keeps a cozy 59 to 65 degrees. (4 degree kansas nights). Approx. 40.00 a month gas bill.

 

[83trekker]

just an FYI for comparision, my shop is 1060 square feet, 10' walls, half the shop has valted ceiling,5" slab, no insulation under slab but installed 2" foam board around the foundation from ground level down 2'. Using 3 300 ft. loops of 1/2" pex, & 1 40 gal. hot water tank with thermostat set at "warm". Keeps a cozy 59 to 65 degrees. (4 degree kansas nights). Approx. 40.00 a month gas bill.

what kind of water heater are you using? Is it loacted in the garage? Whats the btu input and effiecency of it? Thanks got any pics of your setup of the water heater?

 

[BowtieNut]

SprintCC - So far my system seems to be working good in this arctic weather. Last weekend it was below zero for 3 days straight here, and nightly lows were in the -20s, but it didn't seem to have any trouble keeping up. I'm quite happy with it.

PAToyota - I just set the thermostat and leave it. When I first got the system up and running, I set it at 60*. That seemed a little too warm to me for working out there. Lately it's been set on 52*, for the past month or so, and that seems pretty good. Last week I rotated the tires on my truck, wearing just jeans and a sweatshirt, and I was very comfortable. I know 52* sounds low to me, and maybe it would be if I was just sitting on my **** out there, but for working it seems good. Next month I am going to re-do the exhaust system on my "summer truck", so I'll see how it feels rolling around on the floor for a few hours. Oh, and I also have a separate thermometer out there to confirm that these temps are accurate.

Also, I talked to the neighbor again and confirmed. He said his electric bill last month was a little over $175 for just the garage!!! He said based on his summer bills, and how much he's been working out there lately, that the boiler is probably responsible for around $140-150 of that. He said he seriously wants to hook it up off-peak, but our local utility isn't cooperating since he doesn't have any backup heat source. Wow, I'm so glad I went with gas! I'll keep you guys updated as the winter rolls out and I get a better idea of how much this is costing me.

 

[G M]

This is the boiler I am using, http://www.conceptmfginc.com/

I have 960 sqft, 3 zones and I am using an 8 kw boiler to heat it. It has kept up well in the -40F temps we have had here recently. I keep it at 70F 24/7

 

[83trekker]

what did that cost you and do you know how much it is costing you to run?

 

[G M]

The kw sizes cost different, you should be able to get pricing for the size you need at Wolseley plumbing, there is one in Calgary.

I am not sure what it is costing me to operate yet, I have only had it going since November.

 

[cubevandude]

The whole secret to this system is to insulate under the concrete slab with 2 inch styrofoam. This allows you to use a smaller heating system (gas water heater instead of boiler) and prevents you from heating the ground constantly. (the ground stays a constant tempurature so you will never warm it up enough to stop it from soaking up your heat.)

Here's a good link for cheap insulation ideas and also shows the benefits of using insulation.
http://www.instainsulation.com/panels/work.shtml

These are actually waste materials from door manufacturing.( Also called door cut-outs) The best way to install these is to leave a 3/8 to 1/2 gap between each panel and spray foam the joints. This seals it very well. Then place your vapour barrier over the insulation. You can even cover the plastic with sand to prevent it from getting damaged during the concrete pour.

 

[83trekker]

the only prob is i was to dumb to insulate under the pad and now its to lte, so just seeing what everybody is using and paying who also didnt insulate under the pad.