Converting Radiator to Radiant Floor Heat

**Gamby33** · 10-10-2011, 05:45 PM

Good evening,

I am having my bathroom completely renovated, complete gut job down to the studs. Its a small bathroom but has a cast iron radiator under the window and recessed into the wall. The bathroom is on a separate zone and has its own thermostat. I was wondering if i can convert this one room into radiant heating and get rid of the ugly radiator. If yes, what is needed?

Also, i would like to replace all the waste piping while the pipes are exposed, what is the best way and material to do this.

Thanks

Billy

**Tom Sawyer** · 10-10-2011, 06:32 PM

Sure you can. Your oil or gas dealer can run the heat loss and calculations for you and design the radiant loop piping so that the floor heats properly. PVC would be the normal choice for waste and vent piping these days.

hj · 10-11-2011, 06:13 AM

In most cases the radiators will operate at a higher temperature than a radiant panel should. The separate thermostat will NOT control that, so you will need a mixing valve at the supply side of the panel. The material of choice for DWV systems depends on WHERE you are. Some areas use PVC, and others ABS, and while either can be used everywhere, the choice will usually depend on which is more popular, and readily obtained, in a given area.

**Tom Sawyer** · 10-11-2011, 01:10 PM

If he goes with staple up the water temperatures won't change much and even at that, it is usually difficult to get even 1/2 the output of the radiator from radiant staple up.

**Gamby33** · 10-11-2011, 05:55 PM

Thank you both for your replies....

Since this is going to be a total gut job of the bathroom i would like to have the radiant in some type of mortar/cement floor.

Would that not give me the best install?

Or would it be just the same to install over a plywood subfloor?

(There will be no access to the floor from underneath)

Thank you again

**Tom Sawyer** · 10-11-2011, 06:12 PM

Yes a cement floor with radiant tubing will perform much better than staple up but now you are into either a mixing valve or a separator along with a total re-pipe of the boiler in order to get proper flow and temperatures throughout the system. It's not as simple as running some tube and hoping for the best.

**Gamby33** · 10-11-2011, 07:13 PM

Wow, that seems like a lot more work. I guess since we don't use the bathroom heat that often (sometimes we don't even turn the thermostat on in winter) the staple up with a heat transfer plate would be the best, easiest and most cost efficient option?

**Tom Sawyer** · 10-11-2011, 07:23 PM

Na, the best and cheapest option would be to fabricate or buy a cover for your radiator. I'm no fan of staple up. You can go here www.heatinghelp.com for a detailed explanation as to why if you want. I have also written a couple articles on the subject that can be found in the archives of PM I think.

**Gamby33** · 10-11-2011, 08:07 PM

Thanks again.. What do you think of just capping off that radiator and doing an electric floor heating system and calling it a day?

**Tom Sawyer** · 10-12-2011, 03:31 AM

If when you do the remodel you install a vanity as opposed to a pedestal sink, you can go with a toe space heater under the cabinet like a Beacon Morris K41. It's out of sight and provides plenty of heat.