simple questions of a new heater owner

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Old 12-10-13, 08:33 PM
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simple questions of a new heater owner

Hi All,

I recently bought a house which has a hot water heating system and old cast iron radiators. I'm new to radiators and had a few questions i hope someone could help me with. I tried asking the boiler service technician who came recently but he wasn't much help. I'm sorry there's so many :/, i'm just keen


a) Does having painted radiators reduce their efficiency marketably? Obviously there's some insulation in the paint but is it anything to worry about? Our painter said it's best to strip them and leave them bare.

b) I need to remove one of the radiators for repair (its come loose from the wall). To do this i assume i need to shut off the system, drain all the water from the system, turn off the valve to the individual radiator and then remove it from the plumbing. The radiator i need to remove is about 5-6' in length, how many people will this take to move?

c) Can you turn individual radiators off if you're not using the room? I've seen you tube videos talking about balancing a radiator system, backing off the upper story radiators. This would seem to say that if i turn a radiator off it's going to change the flow of my system, is this just a grey area you have to figure out for your individual system?

d) Should we remove our wooden radiator covers with metal grills to improve efficiency? My wife seems to like them but i feel like there should be nothing blocking the convection. Are they really an issue or are we splitting hairs?

e) Should i consider getting foil backed foam to place behind the radiators to reduce the heat that is lost to the outer wall?

f) Can you mix styles of radiators? Ours are old cast iron radiators but we have a new thin fin radiator available for the bathroom. Could this work? Would it just be a case of balancing the flow or will other issues arise?

g) Is banging of the radiator pipe a concern?. Is this just normal heat expansion?


thanks heaps if you read this far, sorry for the long list. I'm open to any links you might have to educate me

oman
 
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Old 12-10-13, 09:08 PM
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I need to ask this first... are you certain that this is HOT WATER and NOT STEAM?

Answers below are presuming HOT WATER. If actually a STEAM system, some answers will be very different!

Obviously there's some insulation in the paint but is it anything to worry about?
No. If you painted them BLACK they would actually radiate a bit more heat, but not enough to make the effort worthwhile.

I need to remove one of the radiators for repair
Show us.

The radiator i need to remove is about 5-6' in length, how many people will this take to move?
How far are you moving it? One person could probably walk it away from the wall if that's all you need to do. If you are picking it up and moving it downstairs, you better have some stout friends!

is this just a grey area you have to figure out for your individual system?
I guess you could call it a gray area... it all depends on how the system is piped. If the radiators are piped in SERIES, one feeding the other feeding the next and so on, you can't close ANY of them without also shutting off the others on the same 'loop'. If they are piped in PARALLEL, with runs from each radiator all the way back to the boiler, then you can shut them off. Be careful room doesn't get so cold as to freeze pipes though!

Attempting to 'balance' heat output by adjusting valves is very tedious... and often doesn't work at all... yes, changing the flow through a radiator DOES affect the heat output, but it's not 'linear'. In other words, closing a valve half way will NOT cut the heat output in half. It's a very NON linear relationship between flow and heat output.

Are they really an issue or are we splitting hairs?
It depends on the design... how restrictive it is. Radiators heat as much or MORE by RADIANT heat than by convective. You can sit in a chair ten feet away from an uncovered radiator and feel warmed by it.

Remember this: Happy Wife, Happy Life!

Should i consider getting foil backed foam to place behind the radiators to reduce the heat that is lost to the outer wall?
Can't hurt. make sure foam can 'take the heat'. Of course it has to be non ugly too. Even a thin sheet of aluminum is good as a 'reflector'.

Can you mix styles of radiators? Ours are old cast iron radiators but we have a new thin fin radiator available for the bathroom. Could this work?
It can... in general the panel radiators won't retain heat in the mass and continue to radiate heat into the room after the thermostat is satisfied though... if it's a 'smaller' bathroom I would think you would be OK... just make sure that the replacement radiator has the BTU capacity you need to heat the room properly.

Is banging of the radiator pipe a concern?. Is this just normal heat expansion?
No, not 'normal'... if properly designed and installed, you shouldn't hear expansion noises. Sad fact is that MANY systems make noise.

Are you sure this is a HOT WATER system and NOT STEAM? Usually cast iron rads with cast iron piping are dang near silent in operation.
 
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Old 12-10-13, 09:14 PM
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Welcome to the forums.

In my old store and shop..... all the radiators were painted silver. They worked fine.

I'm assuming this is a one pipe steam system. You don't have to empty the plumbing. The steam rises into the radiator heating it. When the steam cools it turns back into water and drains back into the boiler.

You will need two LARGE pipe wrenches to disconnect one of those old guys.

A 5'-6' piece of radiator could weigh over 500 pounds.... depends on how tall it is.
This stuff is cast iron and is real heavy.

My radiators weren't covered..... I'm not sure how much a cover affects them.
Foil backed foam behind them couldn't hurt.

I think the pipes banging is usually the pipe rubbing against wood caused by heat expansion.

Since this is a one pipe system.... I don't think you can mix in standard baseboard emitters as they require running hot water which you don't have.

Others will stop by and offer their opinions.
 
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Old 12-11-13, 10:49 PM
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Hi PJ and NJ,

Thanks for the replies.

I'm quite sure i have a hot water boiler as when i bleed my system i purge the air until water comes out. My pressure gauge reads around 12 psi.

NJ, odd that you say radiant heat is the main path of energy, i read somewhere it was convective. But there you go. I guess it does make sense given the name Radiator Still surely if you cover a radiator with a wooden frame then you're relying on the wood to radiate the heat which doesn't really sound efficient.

NJ, see the attached photo of the radiator i need to move. I guess given the size i'd just move it onto the floor and drain it and then lie it on its side. The plaster on the wall behind it needs to be repaired.


I believe some of my radiators are in parallel, at least the ones on the ground floor. It's hard to see what happens to the ones on the second floor. I assume i have one pipe running up the side of the house and then from here it would branch off into the three bed rooms.

I guess i'll have to investigate that banging sound, it's not something that happens all the time. Just every now and then you hear the metal give way to tension it was under and move. Like PJ said, probably rubbing against wood.

cheers
oman

ps i should point out i'm from Toronto Ontario Canada (not NY)
 
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Last edited by oman4eva; 12-11-13 at 11:10 PM.
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Old 12-12-13, 05:39 PM
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oh one last question, i saw a video which recommended automatic bleeding valves for hot water systems. I think that's a great idea as i'm always finding they need a bleed (or at least have a bit of air in them). Any recommendations of auto bleed valve type?

cheers
oman
 
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