Why isn't my house really hot with GCH on so much?

lonestarfan

I have gas central heating in full working order which was installed in 2005 and serviced annually by British gas . I have cavity wall insulation. It's a Baxi combi boiler. Standard 3 bed semi. There's no room or house thermostats. All radiators have individual thermostats on the radiator itself which are up high on every one on number 5. The heating has been on for 4 hours and it's warm but I woudnt say its really hot. My radiators are warm but not boiling hot. I wouldn't say they are so cool at the bottom as to say they all need bleeding. And it's regularly balanced annually. Family are all coming at xmas and they never really feel that warm when I've got the heating on. It's warm but not hot.
Why isn't my house really hot then?

tizerbelle

I am in no way an expert, just another home owner. But immediate thoughts are:
1. what's your roof insulation like?
2. Radiator thermostats can sieze up and this can affect the heating - have read about it on here somewhere but can't remember the details!
3. Have you set the central heating output on the baxi at its highest (mine's just a dial on the front of the boiler)
4. While you're checking that, whats the pressure like on the boiler? Too low and you'll get no heat.
5. Radiators cold at the bottom means there's sludge in the system that needs flushing out. Its when they are cold at the top that they need bleeding to let the trapped air out (and then top up the system)
6. Do you have curtains at all your windows and are you using them?
7. Are there any draughts in the house e.g. under front/back door - these need sorting.
8. Have you got windows open for ventilation.

All the above may be useless pants but start with the smaller/cheaper things before jumping in to expense!

saveallmymoney

Rads should be burning hot.

I second number 3 above.

moneyistooshorttomention

In a nutshell, because the firm that put in the central heating system messed-up their calculations as to what output the radiators would need to be.

I have recently modernised central heating system in house I recently bought. When I queried why one radiator wasn't "doing the necessary" it boiled down to it was their fault. They had chosen a radiator for that room that was not capable of turning out the standard 20/21 degrees Celsius recommended for that type of room.

I had to get them to change that radiator to a higher capacity one.

Clue as to capacity:

- I had quite categorically specified a "double radiator". They had ignored my instructions and put in a "single radiator" (ie a single convector one).

- Different makes of radiator have differing levels of efficiency. From what I could work out the exact same size of radiator and with both radiators being "double" ones could have a different output, down to the variable qualities produced by different manufacturers.

From experience - in hindsight I would have put in writing exactly which radiators were to be "double radiators" (ie double convector ones), rather than telling them and expecting them to listen to me and note down my instructions.

From experience - I would have made it plain I follow standard temperature guidelines personally (ie I expect all my house to be at 20/21 degrees Celsius set on medium on the dial on my radiators), apart from the bedroom ones possibly (as bedroom temperature is 16 degrees from what I remember).

- From experience, I would be checking who the manufacturer of the radiators was - in order to ascertain whether they are one who turns out higher than normal output radiators according to their size or lower than normal output radiators according to their size.

In your case, my suspicion is that some/all of your radiators are only single (ie single convector) ones and/or that their size is inadequate for the size of room they are sited in.

lonestarfan

Very helpful money thank you. I think you could be right and I'd forgotten that someone mentioned that very briefly a while ago in their own home and I completely forgot about it and assumed it didn't aplly to me but actually o can see you might be right. Thanks
I do have a single radiator where I think it should be double - can I just get it changed or do I thne need a new boiler because of capacity etc

lee111s

I'd third checking the temperature that the boiler is set to for the radiators.

To put it in perspective, I live in a 5 year old semi detatched, it's 4 degrees outside and I've had my heating on for 45 minutes and the house is already too hot for me (other half disagrees!) at just over 23.

The boiler is set to economic mode so rads not at max possible temperature but they're still too hot to put your hand on them. Heating won't need to be on longer than the 1 hour it's on for before we go to bed.

Johnandabby

moneyistooshorttomention wrote: »

In a nutshell, because the firm that put in the central heating system messed-up their calculations as to what output the radiators would need to be.

I have recently modernised central heating system in house I recently bought. When I queried why one radiator wasn't "doing the necessary" it boiled down to it was their fault. They had chosen a radiator for that room that was not capable of turning out the standard 20/21 degrees Celsius recommended for that type of room.

I had to get them to change that radiator to a higher capacity one.

Clue as to capacity:

- I had quite categorically specified a "double radiator". They had ignored my instructions and put in a "single radiator" (ie a single convector one).

- Different makes of radiator have differing levels of efficiency. From what I could work out the exact same size of radiator and with both radiators being "double" ones could have a different output, down to the variable qualities produced by different manufacturers.

From experience - in hindsight I would have put in writing exactly which radiators were to be "double radiators" (ie double convector ones), rather than telling them and expecting them to listen to me and note down my instructions.

From experience - I would have made it plain I follow standard temperature guidelines personally (ie I expect all my house to be at 20/21 degrees Celsius set on medium on the dial on my radiators), apart from the bedroom ones possibly (as bedroom temperature is 16 degrees from what I remember).

- From experience, I would be checking who the manufacturer of the radiators was - in order to ascertain whether they are one who turns out higher than normal output radiators according to their size or lower than normal output radiators according to their size.

In your case, my suspicion is that some/all of your radiators are only single (ie single convector) ones and/or that their size is inadequate for the size of room they are sited in.

Doesn't explain why the OP's radiators are only warm - doesn't matter if the radiator is undersized, if the heating system is operating at an average water temp of 75 degrees Celsius then the radiator should be hot to the touch. An undersized radiator will just mean that the room doesn't get to the required temp, not that the radiator is only warm to the touch.

Much more likely that the temperature dial on the boiler has been turned down, or that some other control device (like a weather compensator or delayed start thermostat) is controlling the water temp to improve boiler efficiency, and doesn't realise that you're trying to recreate the Bahamas in your living room....

Johnandabby

lonestarfan wrote: »

Very helpful money thank you. I think you could be right and I'd forgotten that someone mentioned that very briefly a while ago in their own home and I completely forgot about it and assumed it didn't aplly to me but actually o can see you might be right. Thanks
I do have a single radiator where I think it should be double - can I just get it changed or do I thne need a new boiler because of capacity etc

I wouldn't agree with that if your radiators are only warm and not hot to the touch - that tells me that your heating water temperature is low, rather than the radiator is undersized. You need to check the boiler temperature (should be a temperature dial on the boiler) before doing anything about changing radiators or boilers!

In most cases the boiler is sized on hot water demand not space heating, and therefore it is very, very unlikely that your boiler is too small unless you live in a mansion.

But I only troubleshoot heating and ventilation systems for a living, so what do I know.....

sparky260500

Try unscrewing one of the TRV and see if the rad gets any hotter. You shouldn't have TRV on every rad there should be one rad without one on.

sparky260500

Johnandabby wrote: »

I wouldn't agree with that if your radiators are only warm and not hot to the touch - that tells me that your heating water temperature is low, rather than the radiator is undersized. You need to check the boiler temperature (should be a temperature dial on the boiler) before doing anything about changing radiators or boilers!

In most cases the boiler is sized on hot water demand not space heating, and therefore it is very, very likely that your boiler is too small unless you live in a mansion.

But I only troubleshoot heating and ventilation systems for a living, so what do I know.....

So not to confuse the OP i think you mean unlikely

Johnandabby

sparky260500 wrote: »

You shouldn't have TRV on every rad there should be one rad without one on.

That's only if there's a room thermostat, which the OP has said there isn't - you wouldn't have a TRV on the rad in the room with the room thermostat.