I need your help please Piglet John!

[PoptartPoptart]

My mum and dad recently moved into a new property and have a problem with their heating. When they turn it on all the radiators get hot but then about an hour later 5 out of 8 of them go cold (2 downstairs and 3 upstairs). They have had numerous plumbers and heating experts round who charge them a fortune but none have solved the issue. They had 5 new radiators on the advice of one plumber, but the problem persists. As they are in their 70's I'm worried about the cold weather setting in. The boiler is only about 5 years old. Any idea what could be causing the issue? Many thanks for any advice you can offer

Is there a hot water cylinder?

Have any of the radiators got thermostatic radiator valves?

Do the radiators get hot all over or have cold patches?

Where is the room thermostat?

How did they choose these heating people?

Thanks for your reply - I've checked and there is no hot water cylinder.
All the radiators have thermostatic valves.
The radiators have some cold patches.
There is no room thermostat.
They got the heating/plumbing people from Checkatrade.

There ought to be a room stat

The radiators that go cold first probably have their TRVs set low so will go off when the temperature is reached.

If the cold patches are in the middle of the rads it'sludge. If at the top they need bleeding.

The TRV's are set to the maximum level but some rads still go off after about an hour while others stay on.
If it is sludge in the rads how can they get rid of it? One guy mentioned some sort of power flush through the system but even after charging them £200 it still wasn't resolved

photograph the TRVs please

put a thermometer in the room so we can see the room temp.

Feel the rads to see where the cold spots are

£200 is abnormally cheap for a powerflush. How long did it take and what did the machine look like?

I'm not usually keen on BG as they are quite expensive, but they will possibly do a fixed price repair and you can take out a 1 year service contract. It sounds like the other people have cost a lot and achieved nothing. If BG let you down you can complain and escalate.

Checka trade is not fully reliable because the advertisers pay to be listed. Some people say they write their own reviews. They also scour websites like this one and their solicitors demand that unfavourable comments are removed. Personal recommendation is much better, but form an opinion on the work in your friend's house as well.

To find local gas installers, look on www.gassaferegister.co.uk/

www.dailymail.co.uk/news/article-2671559/Can-trust-website-claims-banish-cowboy-workmen.html

uk.trustpilot.com/review/www.checkatrade.com

If you can't find the thermostat they might have placed it somewhere not ideal. If it's in a room that warms up quickly it will shut the circulation down prematurely.

Thanks so much for your help. I'm going over to visit my parents tomorrow evening so I'll try and photograph the TRV's and put a thermometer in the room then and report back. Once again thanks for your help so far

there are people who install CH with no stat, but it is very bad practice.

Thanks for your help, they are getting BG round next week