My heating system is about 30+ years old. The oil boiler is fairly new, but rads original. With the price of energy rising and thoughts about leaking rads, it is perhaps time to change them. They are the basic stelrad type and I wondered what advantage there would be in putting in modern Barlo or similar? What I am looking for is a warmer house for the same cost, or is it a pipe dream?
Assuming that they are internally reasonably clean and not sludged and not approaching leaking point, then thye should be giving as much output as they always did.
Obviously, sludging reduces effective heat output because water doesn't flow in part of the radiator, so if that's the case, a thorough flushing after removing the radiators and taking outside would help.
Other than that, in rooms where you would like more output you could swap them for double and finned radiators with similar wall area and get more out.
If you do, then look carefully where you have multiple radiators connected to 15mm branches. Remember that there is a rule of thumb limit of about 6kW for runs of a few metres in 15mm.
Thanks Andy, I have already flushed the system, so it looks like new for old.
If you replace unfinned radiators with finned ones of the same size, you'll get something like 50% more heat out of each one.
*But* it doesn't come free - the boiler will have to work harder, and will consume more fuel, keeping the radiators hot.The only way you can get a warmer house without increasing fuel costs is to improve the insulation so less heat escapes to the outside world. Have you already got lots of loft insulation, cavity wall insulation, double glazing, draught-proofing, etc.?
If you change old radiators for modern ones the same size, the Btu value will be higher. How will this affect the boilers ability to supply if the collective value is above the boilers output rating?
Possibly, but not inevitably. Depends on the respective designs.
The boiler won't be able to get them up to the boiler's design temperature. If it's a really long way out, then a non-condensing boiler could end up operating in condensing mode for extended periods, and rapidly corrode internally.
You should be able to see how near the boiler's output is to your system currently by observing the boiler operation. With the boiler set to maximum temperature, once the boiler has got the radiators up to temperature and assuming the room thermostat and all TRV's are still calling for heat, see what percentage level your boiler is operating at. If it's a modulating boiler, you'll need to know what the modulation level is. If the boiler doesn't tell you, you could work it out from the rate of gas consumption. For a non-modulating boiler that cycles on and off, work out the total 'on' time as a percentage over a period of time (or you again work out the average gas consumption rate over a period which includes many on/off cycles).
|If you change old radiators for modern ones the same size, the Btu |value will be higher. How will this affect the boilers ability to |supply if the collective value is above the boilers output rating?
Not much! because the Btu/watts radiated/convected to the air depends on the area/surface finish/colour of the radiator, which will have changed little. Boilers have traditionally been much overrated and still are. The insulation of existing houses has been increasing as people want to decrease the amount of fuel used to heat the house.
If not already fitted them how about fitting a thermostatic radiator valve, then at least you will not waste heat.
Er . . except if the new one has fins and the old one didn't, the effective surface area for convention will have increased dramatically.
Thanks Roger,
I have DG throughout, 6" fibre in the loft and cavity wall insulation.
JC
Sounds reasonable, although 8" or more in the loft is now the norm.
Christian.
|> I have DG throughout, 6" fibre in the loft and cavity wall insulation. | |Sounds reasonable, although 8" or more in the loft is now the norm.
When I first did my loft 1 inch was standard or perhaps a bit OTT. It is still there buried under thicker stuff.
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