radiators

[nospam]

Hello,

We've recently moved house and two of the bedrooms are cold. I think the problem is that the radiators are too small for the rooms. I've found a couple of radiator calculators on-line but some are more sophisticated than others (taking into account type and size of windows, number exterior walls, etc) and each has given me a different recommended radiator size! How do I know which one to choose?

If I upgrade the radiators will the rooms warm faster and get warmer? I would think that with a big rad. you could turn it down if it was too hot, whereas you cannot turn up a small rad. past its limit.

If I won the lottery and upgraded all rads. would I hit a problem if the BTUs of the rads. were greater than the BTU that the boiler is capable of?

If I only changed these two rads, hopefully I would not reach this limit nor have this problem. How do I find out the BTU rating of my existing rads and boiler?

Thanks.

[The Natural Philosopher]

The quick and dirty check is to see whether the rads are blisteringly hot, but the room is still cold. If so the rads are too small.

If however the rads are not blisteringly hot, the problem lies elsewhere.

[Roger Mills]

By doing the calcs manually, based on the area and U-value of each surface, the required room temperature, the temperature on the other side side of the surface, and the required number of air changes per hour. [If all these parameters are specifiable in the progams you've downloaded, they should get the same answer, anyway!]

Yes, provided the pipework is adequate. You will need to (re-)balance the system.

Possibly. What really matters is whether the boiler is capable of keeping up with the heat losses of the house as a whole. If the theoretical capacities of the rads add up to more than the boiler can produce, then they clearly can't all run at full capacity - but *still* may be able to make the house comfortably warm.

Measure and note the construction of each radiator - single or double panel, unfinned, single finned, double finned, etc. and find similar ones in a radiator manufacturer's catalogue. This will tell you the capacity. If using more than one source, make sure that the capacities are all based on the same delta-T, and adjust the figures to suit.

There should hopefully be something on the boiler to indicate its apacity - maybe inside the front cover? Otherwise, post the make and exact model here and someone will probably be able to help.

[The Medway Handyman]

True. System could need balancing - read Phils FAQ.

[The Natural Philosopher]

Comparing my response to Rogers..I am reminded of another Roger who was called in to sort a minor problem on a design or radio I was doing. some years back..

He hummed and harred and spent two very expensive weeks covering pages with calculations before reporting to my boss

"The problem would appear to be in the bought in tuner head"

My boss called me in. "What do you say?"

"I told you it was the problem before he was brought in"

"yes, but how did you know?"

"Well I pulled it off and went into the IF strip direct, and the noise went away: took me about ten minutes in all"

[Roger Mills]

OK - but having determined (say) that the radiators *are* hot but the rooms aren't, my response will help him to work out how much bigger the radiators need to be - yours won't!

[roybennet]

I once replaced some radiators with larger ones but the new radiators just wouldn't heat up properly. I had to remove a couple of sections of

1/2 copper pipe and replace them with 3/4 in pipe before the replacement radiators would heat up properly. Just a thought.