How long does your central heating take to heat the house?

TanDiy

Hello, We have just had our warm air heating replaced with a combination boiler, pipes and radiators (70's 4 bed detached house) and would appreciate some advice from others with a similar system. Today the heating came on at 06:30. It was 1 degree outside and the stat said it was 14.5 degrees in the house. We set the stat to 21 degrees. The temperature (according to the stat) did not reach 19 degrees until 09:00 (two and half hours later). It went on to reach 20.5 around 10:15. We just wondered whether this is normal or whether there is something wrong and it should heat up faster. Thanks for your assistance.

neilmcl

21 degrees is quite high and I would expect any house to take a while to heat up to that temp from 14 degrees. My 1920s house is pretty hard to heat and took 2 hours to get up to 18 degrees this morning, minimum overnight is 14 (whether it got down that low I don't know).

What boiler do you have and what temp have you got the CH setting at?

TanDiy

Hi, thanks very much for coming back. It was the 3 hours to go from 14.5 to 19 that we thought was a little slow but maybe this is correct. The boiler is a Worcester Bosch 35kW combi with 12 radiators. The temperature on the boiler for the radiators was set at 80 degrees. We thought it should be lower around 75 degrees but the heating company told us to turn it up because it was taking too long to heat at the lower temperature. We think our bathroom radiator may be undersized because it is very hot but the bathroom is not heating up very much and we are concerned that other radiators might be undersized. Thanks

neilmcl

Or it could be your house is poorly insulated, especially if it dropped to 14 degrees overnight. How big is the house, 12 radiators sounds a lot in an average 3 or 4 bedroomed home. Including towel rails I have only 8 in my 3 bed detached.

FreeBear

neilmcl said: My 1920s house is pretty hard to heat and took 2 hours to get up to 18 degrees this morning, minimum overnight is 14 (whether it got down that low I don't know).

Similar aged semi here. Looking at the heating logs, it is around one hour for each degree Celsius increase (subject to outside temperature). But then my boiler is pretty ancient and insulation is not as good as I would like.

twopenny

Are the walls insulated?

I'm guessing the roof is.

Do the pipes run through the roof, floor or walls?

TanDiy

Thanks for replies. The house dropped to 14.5 last night, previous nights only dropped to 16 last week. The house is common 70's 4 bed detached, one square box for the house and another on the side with a flat roof for the garage! Have 11 radiators (4 beds, 1 bathroom, 1 landing, 1 cloakroom, 1 kitchen, 1 dining, 1 lounge and towel rail in utility room. Its lovely and warm compared to the warm air system it replaced but just wasn't sure if the startup time is normal. The only real problem we have is that the bathroom is not very warm but it is north facing and we had to put the rad on an internal wall rather than one of the two external walls. Need to rethink that one! Thanks

TanDiy

twopenny said:

Are the walls insulated?

I'm guessing the roof is.

Do the pipes run through the roof, floor or walls?

Hi, the roof is insulated but the outside walls are cavity with no insulation. We have concrete floors downstairs so have three pipe drops from the upper floor. No pipes running through roof or walls and boiler is downstairs in utility room. Thanks

Ballymoney

Our house, also a 4 bed detached (1960’s), takes similar amount of time as OP to warm up. Having lived here for 3 winters now, I’ve confirmed to myself the 24hours a day central heating method works best for our house (emphasis on our house, and not every house). I set the thermostat to 20 overnight and 21 from 8am - 10.30pm. Uses same amount of gas, if not a tiny bit less, and the the boiler just ticks over.

We used to just heat between 6am and 10.30pm and it took 3.5 hours of maximum boiler output to get to temp (21c) on cold days.

We use about 28,000 kWh of gas a year and that hasn’t changed the 2 years we’ve gone 24/7 heating.

Anyway, the point of my post is to say the OP’s scenario isn’t unusual.

macman

As above: assuming the heating was on the day before and went off at 10pm or thereabouts, it should not be dropping as low as 14.5C in about 8 hours.
You have told us lots about your boiler and rads, but absolutely zilch about the insulation. Do you have double glazing, cavity wall insulation, adequate loft insulation, draughtproofing?
Bear in mind that a combi cannot provide CH and DHW simultaneously, so if baths or showers were being taken between 6.30am and 10.15am then there would be no heating input during that time.
A combi would not be my choice for a large 4 b/r detached property with 2 or more showers or bathrooms.

EssexExile

Our 1950s 4 bed detached takes about the same amount of time to heat up, I've no idea what it goes down to overnight though. We have good loft insulation, cavity wall insulation and triple glazing so it's just something we have to accept.