Electric for radiant heat?

J.T.

I am new to radiant heating and would like your opinions if I might. I have a customer who is building a 1500 sq.ft. woodshop and would like radiant heating installed. He does not want a furnace or boiler with flames (for obvious reasons). I'm planning on using an electric boiler from Seisco.

My question is, is this really an efficient alternative for a woodshop? The customer isn't going to be living in it, only working for an hour or two a day at most. I'm concerned that once installed, his electric bill will go through the roof. Any thoughts?

Jay

Uni R

A big problem, if...

The will be a big problem if he expects to only have heat when he is working there. In floor radiant in a shop is better suited to maintaining constant temperatures. It is not responsive enough to be used for a few hours as needed.

Dale

Rad tube

If this is a detached building I would suggest gas fired ceiling radiant tube heat. If he wants warm floors he'll have a heck of a bill to keep the place warm with elect mats. However if really well insulated he may find it worth it. Any chance of running insulated pipe from the boiler in the house?

J.T.

Yes, it's a detached building, unfortunately he has a heatpump and not a boiler in the house. I may not have given enough info earlier, we're putting in pex in the concrete slab and using the electric boiler to heat the water.

Carl PE

yep

That concrete slab is going to take all day to heat up.

How about electric radiant in the ceiling, where you don't have so much mass?

J.T.

Good point. That is why I came here! Thanks

hr

Of course it depends on

your electric rates compared to other energy sources. we've heard some .04 per KW hours from some of the regulars here.

Radiant ceiling sounds more geared to that useage. Personally for the tubing cost for that size slab I'd stick it in the slab and ceiling!

If he (or she)gets booted out of the house he may prefer a warm slab

If you go hydronic they have the ability to select their energy source. Electric may be good now, perhaps a 90% plus gas or LP may look better if prices drop?? Or vice versa.

hot rod

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Lurker_2

re

furnaces/boilers are used in wood shops all over the planet. Unless you live in florida, the electric bill is gonna be killer.

sealed combustion

My business space used to be a cabinet shop, scorched air condensing no fires.

JohnWood1

NO BLANKET STATEMENTS PLEASE

until you compare the cost of each btu for each fuel, you really don't know this guys situation. I have seen many a case where it is much cheaper to use electricity than LP

sy308_2

gas heats water 2.7 times less expensive than electric here

I agree with the posting wondering on cost of electicity. One needs to calculate the cost of fuel in order to know how much this project will cost to run. In my area, we looked at heat pumps as a cost return item to heat my house. Calculations showed electric was 2.7 times more expensive to heat my home at $0.14/KwHr than gas was. Even factoring rises and projected rise in gas prices vs electric we could not get any payback in my lifetime. You also need to know the location of the project. What is the heating season like? Personally, I don't see any problem with using a direct vent boiler. They are safe in this application with fumes and are very efficient. Also, the slab would like to be constantly heated in order to gain the efficiency of radiant heat. Is this business or hobby? Why not use hydronic wall units to do heating and A/C? Perhaps you do not have natural gas but LP in some rural location? You really need to look at this in more detail or expand on your knowledge here so that people know better on how to assist you. Good luck.

J.T.

cost of electric

We're in Va. The cost of electric here is between .04&.06kWh. I've seen some formulas on comparing costs between electric, nat., propane and oil but can't remember where. It's a hobby for this customer. I'm getting a lot of "It's so expensive", which is one reason he doesn't want a boiler. He almost went with an internet Co. and installed it himself. They told him he could use a standard 30 gal. electric water heater. Like I said, I'm so new to this and looking for direction so it can be done right or not at all (by me). The total heat loss is 26,000 btu/hr.

Joe Brix

Heat source not the issue

But me must be told that the slab temp must be maintained all during the heating season. Radiant response is slow so he probably cannot setback the space below 60° or it will take 8 to 10 hours before the room comes up to a comfortable temp. I hope he's got plenty of amps out there. You could also look at some of the gas wall hungs that could be mounted on an outside wall. If cost was an issue, why did he go radiant? Gas or oil direct vent wall heaters might have been a better solution.

J.T.

He wants radiant because a friend of his has it. His friend has a Wirsbo system with an electric 50gal. hot water tank heating his woodshop (approx.1500 sq.ft. also). He doesn't want to pay for a boiler due to the cost and just wants to use the hot water heater. He's dead set on putting it in the concrete and keeping the temp. set at 67 (no set back). I've explained to him that I can't be responsible for his design and electric usage and he's ok with that, so well see how it turns out.

Uni R

Set it and forget it...

No problems with 67 and hold. A key thing may be convincing him to make that workshop even tighter tight and better insulated than proposed. I believe the correct term is "super-insulated". Could you get the heatloss lower than 26,000MBTU? Get it low enough and the fuel source becomes less and less of a factor.

J.T.

At this point, I can't convince him to do much else. It was like pulling teeth to get him to insulate under the slab and the perimeter! He's on board with the water heater and if it doesn't work or the bills are too high for him, he's agreed to changing it out for a small boiler.