Radiators take an age to warm up. Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[Rayo]

I am having a couple of problems with my radiators.
The first is that when I have the boiler set to hot water only, the rads come on too.

The second and most frustrating, is the time it takes for the radiators to actually heat up.
On a good day it can take 1 1/2 hours.
When I say heat up, I mean fully. However it can take an hour just to get any heat in them.
I've tried turning the downstairs rads off and just having the upstairs on first. Switching them all off and putting them back on one at a time. I've bled them too, but none of these solve the problem.
Hope someone can shed some light on it.

[plumbbob]

There could be several things causing the problem you describe but as you have not described your system in any detail, it is very difficult to offer any useful advice!

Is the boiler big enough for the number of radiators and firing correctly? Is the pump running fast enough (assuming you have a pump)? Is a bypass too far open? Is water bypassing the heating circuit around a tank coil? What zone valves do you have (if any)?

The more information you give the more useful the replies.

[Rayo]

Thanks for the reply plumbob.

The system has managed without any problems in the past.The pump appears to be o.k. How do I check if it's running correctly?

I have no idea what the bypass is, what zone valves are or if the coil is being bypassed.

[plumbbob]

Listen to the pump. Is it quiet with just a gentle hum? If so probably ok. Does the pipework around it get hot quick when the boiler first fires up? If so ok.

Trouble is without a description of your system there is little anyone can offer as there are just too many possibilities.

[Rayo]

Thanks for your help so far plumbob.
I'll check that out.

[htg engineer]

If the downstairs radiators get hot (eventually) I would assume the pump is ok.

I'd be looking towards the gas pressure.

Get a RGI to check the gas pressures are set correctly. The burner pressures and the working pressure at the gas meter.

If the burner is staying on low rate it will take ages to heat the radiators.
Even older boiler have step up regulators, maybe the gas valve does not open for high rate.

Another reason could be the gas meter governor, if the working pressure is too low, again it will take ages to heat the water.

htg