Need help with radiant heating

[Jaromir Svoboda]

Building new shop and I like to use electric water heater,but dont know what size , brand ,with tank or tankless.Need help.
Shop is 806 SF.10 ' walls.

Thank you.

[Dan Hintz]

If you're not taking showers out there, a small heater is more than adequate. If you rarely will be using hot water, a tankless would be the most efficient. Be aware, though, that the tankless units require a certain minimum flow before they turn on, so expecting to trickle out hot water isn't going to happen. That, and they take one hell of a lot of current.

Edit: Okay, I'm an idiot... forgot when replying this was for radiant heating. A small heater should be able to keep up with your heating requirements and will have a much lower initial investment than a tankless heater... consider it will be running for long periods of time, the tank heater will probably be the more efficient of the bunch, too.

[Jim Tobias]

Jaromir,
My shop is just over 1000 sq ft and I have radiant floor heating and use a gas 30 gallon tank. I was ready to put in a tankless on demand(Rinnai) when I switched over the hot water use for our house(separate area) about a year ago, but the plumbing installer(who I know personally) advised against a tankless for the radiant floor use. He said that it would be cycling on and off far too often and would likely not last as long in that situation. I went with their advice and have never run out of hot water in the shop (radiant floor heta or hot water at the shop sink).

Jim

[Ken Fitzgerald]

Another thing to consider is local code requirements. I wanted radiant floor heat in my shop but local code required a water source in the shop or a specially designed safety system. The costs of putting water and sewer lines into my shop or having a special safety system drove the price out of my means.

[Tom Godley]

First you need to find out the heating load for the space - that way you can determine the BTU's needed from the heating unit. If it is a large space in a cold climate a regular water heater may not provide enough output to heat the area without some type of back up. Using a domestic tank style water heater is not allowed is some areas even when it is not used for potable water.

I can not recommend a brand -- the number of makers is small and so many are just relabeled. You can buy water heaters that incorporate a separate coil inside for the radiant connection -- they are obviously more expensive. They work especially well with master bedroom additions where another water heater needs to be installed anyway -- the coil setup allows for a simple heated bathroom floor / towel warmer.

Often with an electric radiant they use a small electric boiler -- they look like a big lunch box - come in many BTU outputs. You size them using the heat load and then use a mixing valve to keep it happy. Simple thermostats control the system.

[Brian J. Elliott]

Radiant floor heat done right is expensive. You might be able to by with a small electric heater but the system may not be as efficient as it should. I install and work on alot of tankless waterheaters. At this point I have not seen an electric one that I was impressed with. Most radiant systems have boilers. For a 800 sq foot shop I would probaly look into one of the small HVAC systems that is offered now.

Here are some links.
DIY radiant floor heat http://www.radiantec.com/index.php

Small space heat pump http://www.mitsubishicomfort.com/en/consumer/product-solutions/solution-advisor

Good Luck

[Jaromir Svoboda]

I will go with electric boiler.
Thank you.

[Joe Hennessey]

It's quite feasible to heat a small building with a water heater. Gas is usually cheaper than electric, but not always depending on local prices and availability.

Where are you? Nova Scotia, probably not gonna work unless your building is well insulated. Arizona no problema.

In order to answer your question much more info is needed.

How many degree days is your heating season?

What kind of building? Stick frame? 2x4 or 2x6? What kind & how much insulation?

If your're looking for radiant heat in new construction a concrete floor is likely, are you going to put foam under the floor? If not you'll be heating the planet and your shop.

You need to do some research before you decide what you need but those little boilers are pretty pricey compared to a water heater.

http://www.jlconline.com/cgi-bin/jlconline.storefront/4c48fe4f01ecae2027180a32100a060e/Product/View/9811usin (http://www.jlconline.com/cgi-bin/jlconline.storefront/4c48fe4f01ecae2027180a32100a060e/Product/View/9811usin)

This is a link to an old article from the Journal of Light Construction. I don't know what it cost to download one article, but this one has everything you'd need to know with pictures and diagrams of how to do it with a water heater.

You say you're building a new shop, are YOU building it? If so there's a lot you can do to make the heating load smaller/cheaper.

Joe H

[Jaromir Svoboda]

I'm west of Chicago,IL.I put 1.5" insulation under slab ,2" insulation outside,2x4 walls 10'with R13,806 SF.I will put R 38 in ceiling.
I like to use electric boiler so I dont have to dig 80' long trench for gas line.
I saw some 12 KW electric boilers at Menards for $ 500