And some days you learn many, many things

kellapitter · November 2014

Hi. I am, admittedly, an HVAC ignoramus. But I am diligent. So, I have an old 4-tube, 6 section cast iron radiator in my 10.5 x 5 bathroom (roughly 32"H (excluding feet)x 6" depth). I have computed a 3570 BTU output at 170 degrees in Philadelphia PA region, and it heats the bathroom nicely. Based on the size of the room I have computed a 2200 BTU output required, though I forget the water temp. I haven't a clue what temp my system runs at, though I'd be happy to check the dials now that it's winter. If I knew which dial to check. Ceiling is 7.5' to accommodate old recessed lights. I hope to make it a bit higher. Only demo will tell.

I am remodeling and everything I am designing for this bathroom is to make it appear LARGER, so have budgeted a wall-mounted radiator in white to be installed. The 2" depth of the Runtal wall panel is very appealing. The price quoted by my installer is not.

My questions are:
What is the BTU I should be going with in order to size the radiator?
What is the depth of the Myson T6?
What are other manufacturer/brand options to explore that would have the narrow depth?
Can the existing radiator be isolated for removal, or should the whole system be drained?
Is it wise to perform this operation in winter?

Steamhead · November 2014

Don't do it unless you want the room to be uncomfortable. Unlike a cast-iron radiator, that steel Runtal will cool off very quickly when the circulator shuts off.

You can still get cast-iron radiators that are much slimmer than older ones with the same heat output.

SWEI · November 2014

Myson T6 is quite a bit pricier (around 50% upcharge IIRC) than their Select line. The single panel models protrude 4-1/2" from the wall including brackets. Double panel increase that by one inch.

Runtal specifies two inches, but I believe that increases when you add fins, which are necessary to get comparable outputs per unit area.

kellapitter · November 2014

Oh yes, and what is a fin?

kcopp · November 2014

I agree w/ Steamhead. If you must change the rad keep the Cast. The heating and cooling properties are not that same.

KC_Jones · November 2014

I will third what steamhead said. Cast iron has mass that allows it to stay warm for a long time. Steel much more readily gives up it's heat. There are tons of old and new rads around if you look for them. Here is a link to a thread showing an old cast iron panel rad that is only about 3 1/4" deep.
http://forum.heatinghelp.com/discussion/151649/cast-iron-rads-for-sale-near-pottstown-pa#latest
Not sure what the pros would think of this, but there is also cast iron baseboard?! I have zero experience with that though.

kellapitter · November 2014

I like that little one. Would it be large enough to heat the room? I never heard of a one-pipe system. How does that work? My radiator has two pipes through the floor.

FranklinD · November 2014

Also agree on keeping the cast iron somehow. We renovated our small bathroom last year and installed a towel warmer radiator. The rated output was higher than the little cast iron rad (EDR of 21 - hot water heat). But damn was that bathroom COLD. We reinstalled the cast iron radiator. It's all about the mass in my opinion. It heats up and stays toasty for an hour after the cycle.

SWEI · November 2014

Is this a steam or hot water system?

With ODR and constant circulation, panel rads will produce very similar output when properly sized. If you're banging 180˚F water on and off, the cast iron will maintain a much more even temperature.

kellapitter · December 2014

Thanks everyone for your input. I found a 3-tube cast iron (refurbished!) on the internet. At 21" (12 sections, I think) x 25" Ht. it should be similar in btu output as my existing described above. Any thoughts on that? Will I be able to lift it?

kellapitter · December 2014

This is the unit I found. It meets Btu requirement, appears to be refurbished, but what is that big gold thing at the top? My piping would be at bottom. Is this a steam radiator?

Steamhead · December 2014

That radiator came from a Vapor system.

The gold thing at the top left is where the supply valve was connected. It is probably 3/4". The one on the bottom of the other side is where the trap was connected- it is probably 1/2".

Piping a hot-water radiator this way will work, but you will need to add an air vent to bleed the air when re-filling the system.

One or both of those bushings will need to be changed to match the size of the existing piping, whatever that is.

Best thing to do is have a pro handle this.

kellapitter · December 2014

Thanks, Dan,
The pipes to and from my existing radiator are I" OD. I will not be the installer, but I have to purchase the radiator for him. I want to make sure it will be right. This radiator, perfect in size, condition and price, may not be worth the extra trouble to retrofit and long distance for me to pick up.

BTW, could you guess what a 21"x25" 3 tube might weigh?

kellapitter · January 2015

Thanks to all for your help with my radiator project. I sacked the new steel radiator idea and found a cast iron which had been primed but not painted. It is a wee bit smaller in terms of BTU output compared to my existing radiator, but is the perfect depth and nice size. It is now painted and awaiting a pressure test by the plumber who will install it soon.

So, provided everything goes smoothly with the new one, I will soon have a nice 4-tube, six section 38" height radiator for sale. Never been painted, and works fine.

And some days you learn many, many things

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