Heating takes up to 1 hour before rads are hot

[ferrytrip1]

Hi, as the topic says our heating takes an age before the rads get hot enough to heat the house. We have lived here for 10 years and its always been the same. What could cause this?

We had a new boiler and pump 4 years ago. The system was not flushed. Could this be the problem? Would flushing the system improve the wam up time?

Thanks

Simon

 

[Axel]

Do the rads nearest the boiler get hot to touch quite quickly, or is it all of them equally lame?

 

[Temprise]

Hi, as the topic says our heating takes an age before the rads get hot enough to heat the house. We have lived here for 10 years and its always been the same. What could cause this?

We had a new boiler and pump 4 years ago. The system was not flushed. Could this be the problem? Would flushing the system improve the wam up time?

Thanks

Simon

Could be a number of problems.

You say the boiler and pump were changed, what about the radiators, pipework etc?

Was a heat loss calculation and radiator sizing method done during the installation?

A very dirty system will give you poor circulation as will undersized system pipework.

How do you use your controls?

Regards.

 

[oilhead]

What boiler do you have? Is it gas or oil?
How big is the house?
How many radiators do you have?
Do you have to heat up water as well?

 

[ferrytrip1]

House is some 28 years old. 4 bed house with rads in each bedroom upstairs plus 1 in landing, bath, ensuite and a heated towel rail. Downstairs 6 rads in 4 rooms plus the hall.

All were single rads without the convection fins (original fit). About half have been replaced with modern rads using nearest equivalent sizes during decorating.

Gas Worcester Bosch conventional boiler to heat water aswell. 15 mm pipe throughout.

I have timer in the garage to control both HW and CH. HW is timed 3 times a day. CH is on all the time and controlled via pgmable stat in the hall. Bolier fires up on demand OK and quickly gets to temp as shown on the front. Pump has 3 setting, I have just experimented with the highest setting, but it is quite noisy. no results as yet.

Its not a new problem, just become more noticable during this cold spell. Bathroom rad is closest and warms up first, downstairs and some bedrooms take up to an hour before gettin to full heat.

Thanks for the replies

Simon

 

[ferrytrip1]

Also there are no cold spots on the rads and when warm they are very warm

Thanks

 

[Axel]

15mm pipe throughout? That will seriously affect warm up time in a house of that size. Fifteen radiators, I have counted, fed from 15mm artery to boiler?? That is likely to be the problem. SOME of this pipework would need to be at least 22mm to get things circulating efficiently.

 

[ferrytrip1]

I thought about this when I woke this morning. 22MM from the boiler and in the airing cupboard. 15MM coming up from the floor to the rads. Cannot comment on the pipe sizes below the floorboards or concrete etc.

Simon

 

[D_Hailsham]

All were single rads without the convection fins (original fit). About half have been replaced with modern rads using nearest equivalent sizes during decorating.

If you replace an un-finned radiator with a finned radiator of the same size you increase the potential heat output by about 64%. Unless you install a appropriately larger boiler, you will not get this extra heat. Central heating radiators are not like electric fires.

 

[Temprise]

I thought about this when I woke this morning. 22MM from the boiler and in the airing cupboard. 15MM coming up from the floor to the rads. Cannot comment on the pipe sizes below the floorboards or concrete etc.

Simon

What heat output does your heating system have?

If the output is above 18 KW, the flow and return pipework should be increased to 28mm (central heating design spec).

Regards.

 

[D_Hailsham]

If the output is above 18 KW, the flow and return pipework should be increased to 28mm (central heating design spec).

It all depends on the temperature differential. A boiler running with an 11C differential will need 28mm for an 18kW boiler, giving a velocity of 0.725m/s. But if the differential is 20C, 22mm will be OK, giving a velocity of 0.67m/s.

 

[Agile]

For us to be able to comment positively on your problem we would need to know the flow and return temperature at your boiler and the power the boiler is consuming as measured at the gas meter. See FAQ on gas rating.

Or we could just list a wide range of possibile faults which will not help you at all.

Tony

 

[jackecole]

system balanced properley?? manual valves open fully?? pump powerful enough, is it a 5m or 6m head pump? burner pressure of boiler adjusted high enough (if range rated) boiler stat turned up fully??