How long to heat your house

ajbell

Modern 4 bed detached with non condensing boiler.
Temperature only rises by about 1 degree per hour
So in the morning it takes about 4 hours to go from 13c to 17c. Is this normal?. It's an 11.7kw boiler.

Also what kwh/units of gas do you use at this time of year in one day?.

System

ajbell wrote: »

Modern 4 bed detached with non condensing boiler.
Temperature only rises by about 1 degree per hour
So in the morning it takes about 4 hours to go from 13c to 17c. Is this normal?. It's an 11.7kw boiler.

Also what kwh/units of gas do you use at this time of year in one day?.

Do you mean non condensing? I ask because your boiler seems to me to be rather small for a 4 bed property. I have a modern 5 bed home with a 24kW non-condensing boiler. My set up is slightly unusual in that the radiators come on at different times to achieve 18C at 7.30 am. They usually come on sometime between 6.30 and 7.30 to achieve the target temperature.

When the boiler is full flow, I measure about 20kWs/hour. It then drops off rapidly once 18C is reached: we are at home all day and turn up individual radiators as required. Yesterday, it was about M6C at dawn. We used 75kWhs for the whole day.

ajbell

Yes it is non condensing ( conventional) rated at 11.7kw.

[Deleted User]

Modern 3 bed detached with a 24kW condensing boiler. Heating on from 6:30 am to 10:30pm to maintain a temp of 20C using 50 kWH daily currently. Took 1:45 hr this morning to reach temperature

ajbell

So that's about 4.5 units.

[Deleted User]

Yep 4 and a bit units a day

System

ajbell wrote: »

Yes it is non condensing ( conventional) rated at 11.7kw.

As I said, it looks to be on the small size. This is a typical comment about boiler size:

To give you an example of how much heating power you need, in the late 90’s a common boiler of choice for a 4 bedroom house with a cylinder was an “Ideal Classic HE 15”. This boiler would typically run an average size water cylinder and approximately 12 radiators. Its output was 15kw. A 24kw boiler usually does heating at 18kw. So wait a second, your telling me a 24kw boiler will run my 4 bedroom house? Well aslong as the engineer is confident the pump is the right size and you don’t have massive hot water requirements, yes! -

Your home will only heat up if the heat going into the house exceeds the heat that your home is losing. Clearly, the colder it is outside, the greater the heat loss. Four things to check:

A. Do you have CH and HW on at the same time. If so, I suggest that you heat your HW for 30 mins before you need your CH to come on.

B. Check your boiler temperature. Is it turned up for Winter use?

C. Are all your radiators getting hot - top and bottom.

D. Boiler service up to date?

matelodave

What temperature is your boiler set to and do your radiators get hot all over. Have they got TRVs,

Does your boiler also heat the water in which case you should have a room stat, tank stat and diverter valve that sends the hot water either to the tank or to heating. The boiler isn't big enough to do both at the same time, in fact it sounds a bit on the small side, so you need to sort your timings out to get the hot water hot before you try heating the house.

Check that the diverter valve is working properly by making sure that it's only sending hot water to the tank or rads when the appropriate stat calls for heat

I'd guess that you need your boiler turned up to around 70-75 degrees to warm the house a bit quicker

I've got an 11kw heatpump which runs at around 35 degrees which takes about 36 hours to heat the house from stone cold (140 sq.m detached bungalow) so we don't shut it off but just turn it down a couple of degrees overnight and during the day.

Cardew

I am surprised an occupied house drops to 13C overnight.

You say 'modern' 4 bed detached; yet it has a non-condensing boiler? So how old is house and what standard of insulation?

I would have water temperature set to maximum. Presumably it is not a combi at only 11.7kW, so ensure that hot water for taps etc is not being heated at the time you want to heat the house - it can be on before you need heating i.e. overnight.

As said above, check TRVs and that radiators get hot all over.

ajbell

The house is only heated in the morning as I don't get home until midnight, that's why its very cold in the morning.
House is 15 years old. All radiators work fine and get hot all over.

grumpycrab

ajbell wrote: »

it takes about 4 hours to go from 13c to 17c.

1. In which room are you recording these temperatures
2. In which room is the Central Heating thermostat