LP water heater?

I have a commercial 80 gal LP gas water heater that we only used for one year before we quit milking cows. It does not have a power vent but used a chimney. I want to put it in my new shop and use it to heat my floor. Rather than a chimney can it be changed to a power vent system? The units with power vent just have a two inch pvc pipe that vents thru the wall. Thanks Tom

On working, I'd guess it's all about volume, discounting the PVC part which could be a show stopper. Without calculating, area of 2" vs 3" is half and if 4 inch would be ?. So forced air would have to increase the volume by that ratio to keep things in perspective when the fire is lit.....so you need a sensor to sense that and turn on the vent fan when the flame is present, again just a hip shot.

However, PVC is temperature limited.

Then you look at where does the 2x or 4x volume of air originate? Comes up through the flue across where the fire is attempting to burn from the opening where access to the burner is located. Seems to me that it would blow the fire out at least on that side and you would have raw gas accompanying your vent gasses..

I think you need to reconsider!

Since we are working with GAS here, no shortcuts are permitted.

So, check with the mfg. to see if a retrofit kit is available for that exact unit.

It involves more than a fan, there's an interlock circuit that won't allow the burner to fire unless the fan is running and/or air is moving, and perhaps other burner changes.

Also (and I may be wrong here), I wonder if a standing pilot unit CAN be power vented through the wall (if that's what you have).

That being said, a gas water heater would have TERRIBLE efficiency for space heating vs. a modern high efficiency furnace.

That would be a difficult and chancy change.

The ones with power vent have all the necessary electronics to control the vent motor, and to shut down the burner should something go wrong.

I think you could vent it through the wall as it is, long as it didn't have too far to go and you used the proper pipe. Might look through the install manual, find it online if necessary, see if it can be done.

I wouldn't try doing it. I bet that unit actually says n ot for space heating right on it. There are tanks made to do exactly what you want. Any tank you buy will be cheaper than an insurance claim. Remember propane is very flammable and sinks in the atmosphere it's heavier than air.

You might want to look into a boiler and circulating pump to heat your shop floor. I don't know if a household water heater will work well in a recirculating system.

" I don't know if a household water heater will work well in a recirculating system. "


I've seen that done more than once, it works very well, but as I wrote before, efficiency would not be good by modern standards.

Depending upon how low the temp setting goes on the WH, a recirculating loop and/or tempering valve may be needed because of the under-floor system.

It would probably be cheaper to put a double-walled steel chimney up the outside of the building than to convert the water heater to a power vent unit, if that's even possible.

That water heater will do a good job heating the floor i know of several places thats what they used even for livestock a standard 4in pipe will work for the exhaust just fine you dont neede a power vent. Get with a contractor who does in flook radiant heating so you get the lines installed correct using insulation under the lines ect those are the best way to heat you will love it.

Short answer: no.

An 80 gallon heater will use up a lot of floor space. There are now small demand heaters specifically made for radiant heat. <a href="http://www.menards.com/main/heating-cooling/hydronic-radiant-heat/radiant-heat-boilers/c-8519.htm?Spec_FuelType_facet=Natural+Gas&Spec_FuelType_facet=Propane">Menards carries them</a>. The only downside is that they typically need a bigger gas line than a conventional water heater.

I have a 30'X30' garage/workshop with tubing in the floor for heat. I use an 18 gallon electric water heater for heat and it keeps the shop at about 55 degrees all winter.It's been heating it for about 4 years now, Don't let anyone tell you a water heater won't work. When I lived in Wi. I built a new shop 24 by 48' and had that hooked up to heat with a 40 gallon gas heater, worked fine. Was told it would take forever to reheat it after 2 weeks shutdown for vacation, wrong, took 3 days. Both the buildings were verrry well insulated. I new other people out there who used water heaters to heat buildings too. My son in Wi. used an outdoor woodburning furnace to heat the floor in his shop.

Probably not very efficient.

I think that the water heater will be just fine. We put down plastic then a layer of 2 inch pink foam board that we put our heat tubes on and then 2 inches of sand then concrete. Side walls are insulated with 2 inches pink foam board and then we sprayed in 2 inches of spray foam to seal everything. The ceiling has over 18 inches of cellulose blown in. The shop is so well insulated that we run an air conditioner in the summer to keep it cool. I know of some other shops that use a water heater as well. I have an expansion tank and a circulater pump as well. I guess I will just cut a hole and run a chimney up the outside. I also have an oil burner furnace if we need more heat. Tom

Hot water heater will work fine. But consider one point, you will be heating 80 gallons of water, your tubing may hold only 5 or 10 gallons. You are heating a lot of water, in your tank. It would be much more efficient to heat only a few gallons of water. How low can you set the water temp? You really do not need the water to be much more than 100F. I have heated floors on all levels of my house including the garage. I use an electric boiler that holds may be three gallons. The heating elements (4) are the same as in my hot water heater. I would look at what is available at Menards.

Tom I will disagree with the majority of the posts here. You can add a power vent to the water heater as long as it is electrically controlled. Meaning the water heater has a control that sends current to the gas valve to come on. Your water heater might have had a power vent as an option many do. So check for a KIT to use on yours. Many of the older power vents where added on when the water heater was installed not at the factory. You can buy kits on Ebay starting at about $75.

Even if there is not a kit for your water heater model,it is just a fan that goes where the vent currently goes. You can get one off a similar water heater or even a small furnace and make it work. You hook it up to a relay that is turned on when the gas valve is opened. I use a timed delay relay that stays on for one minute after the power is cut to it. This way you know any fumes are blown out even after the burner shuts down.

I have switched all my rentals to power vents. Water heaters and furnaces. You just have less trouble with them over the open vents.

In a shop I would mount the water heater on a platform at least 18 inches off the floor. This is because gas fumes stay at floor level. So you may not smell them but there could be flammable amounts at the floor level.

National Fuel Gas Code 2002

Chapter 8 Equipment Installation

8.1 General.

8.1.10 Installation in Residential Garages.

8.1.10.1 Gas utilization equipment in residential garages and in adjacent spaces that open to the garage and are not part of the living space of a dwelling unit shall be installed so that all burners and burner ignition devices are located not less than 18 in. (460 mm) above the floor unless listed as flammable vapor ignition resistant.

Another thing to consider regarding using an 80 gallon heater. If you intend to frost-proof your system so you can leave the heat off, it's going to take a lot of antifreeze. The cost of 40 gallons of propylene glycol will go a long ways towards buying a smaller heater or boiler.

> I have switched all my rentals to power vents. Water heaters and furnaces. You just have less trouble with them over the open vents.

JD, I'm a bit surprised by that statement. We have only non-power vent water heaters in our home and rentals, and they've been by and large trouble-free. Likewise with our furnaces; the only one to give any trouble is a an older high-efficiency power vented model.

I recently helped a friend replace the power vent water heater in his home; it was the second power vent heater he's replaced in the past ten years. To be fair, though, it seems the drain line wasn't installed in the exhaust, so condensation was dripping back inside the heater and rusting it out.

(quoted from post at 21:45:31 12/05/16) &gt; I have switched all my rentals to power vents. Water heaters and furnaces. You just have less trouble with them over the open vents.

JD, I'm a bit surprised by that statement. We have only non-power vent water heaters in our home and rentals, and they've been by and large trouble-free. Likewise with our furnaces; the only one to give any trouble is a an older high-efficiency power vented model.

I recently helped a friend replace the power vent water heater in his home; it was the second power vent heater he's replaced in the past ten years. To be fair, though, it seems the drain line wasn't installed in the exhaust, so condensation was dripping back inside the heater and rusting it out.

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Mark the trouble I have with the vented heaters is wind. I was getting several calls a month in the real windy months. Even with long vents I was getting pilot light blown out by down drafts. The add in the birds and wasps on the furnace vents I much prefer the short plastic pipes that I have screens over.