How to recess a radiator....

Alan(OnVacationInOregon)Forbes

We did a commercial job in Berkeley about 5 years ago where the owners wanted the (Runtal) radiators recessed. Fiberglass insulation was used in the walls, but nothing other than sheetrock was used around the radiators. Even though the radiators run at 180°, the convected air doesn't get above 70°. And because most of the heating is done by convection, I didn't see a need for a reflective surface.

amy_3

How to recess a radiator

Hi,

For starters, the house was built in 1937, and we are in the process of switching from steam to hot water heat.

I'd like to recess an old Sunrad radiator into the exterior wall of our kitchen. I don't know where in the room the radiator was originally, I think it just wound up where it is during a remodel.

After reframing the opening, what should it be lined with?

I ask because the openings for our 3 other Sunrads are lined with what reminds me of the asbestos cement siding on the house I grew up in.

Thanks for your help!

Josh M.

I wouldn't do it unless you can give it ALLOT of clearance. Radiators rely on air stratification to heat. If the air can't move freely around the radiator your heat capacity will be greatly diminished.

amy_3

This is a cast iron convector type of radiator. It was meant to be recessed. I've attached a Burnham brochure; this radiator is just an older version of their radiant model.

I originally found out what it was by looking at an old ad on this site but I can't find it at the moment.

Thanks, though.

Josh M.

I stand corrected. By your initial description I got the wrong impression.

Generally speaking you don't want to recess on an exterior wall at all. There really aren't any miracle insulations out there that will keep the heat from being drawn to the outdoors.

However if it were me I would get a good 1" thick (at least) reflective barrier foam board insulation layer before installing the radiator and seal ANY possible air leaks to the outdoors.

I am sure however that some of the old timers here on the wall will have some great tricks though!!

amy_3

I appreciate your help.

It's hard to describe them, since they're neither radiators nor convectors. Or maybe they're both.

I've attached a picture of one of the recessed Sunrads to make it clearer what I'm asking about.

bill nye_3

Amy

I converted my in-laws cottage from steam to hot water. It has the same recessed convectors you have and it was also built 1936-37.

I used 1/2" beaded styrofoam with aluminum foil both sides. It is the stuff used by vinyl siding installers. It may not be the best thing going, but is something. The foil reflects the heat, it insulates a little, and it is not so thick that it pushes the radiator out into the room.

Steamhead (in transit)

Why are you

getting rid of your steam system?

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amy_3

(Yikes! I'm still getting the hang of this board! I answered this as an email, but for the record...)

Hi Gordo,

The reasons we decided to go with hot water are:

1. The 14 y.o. boiler is cracked and out of warranty.
We're buying a new one regardless of the system.

2. The tankless coil we have for hot water works
better in theory than in practice. It's also
inefficient compared to the indirect fired water
heater we can include with a hot water system.

3. We'd like more headspace in the basement. With
the iron pipes gone, we could use it as living space.

4. With hot water, the boiler won't blow up (just
kidding;)

Cheers

amy_3

A little insulation is a lot better than none. I wasn't sure what would be thermally stable behind this radiator after seeing that cement stuff behind the other radiators.

Thanks!

ScottMP

Hey Mr. Forbes

HOw ya been pal ? Been a long time since I've seen your name on a post.

Are you still semi-retired ?

Scott

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ScottMP

Amy

you on the right track. These are designed to be recessed in the wall. Not all the way, but at least half way. I've used a lot of them over the years and they worked fine. As Bill Nye said, put one inch of foam board behind them with aluminum backing, they'll work fine.

These are designed to for part convection and part radiant out put.

Scott

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Hvacman

In my house...

When I removed mine there was nothing but sheet metal behind them... They are gone now.