TRVs / One radiator cold

[cmca]

Hi

Getting to the end of my tether with our central heating system. Please help.

1. Boiler: Vaillant TURBOmax Pro/2 E

2. Recurrent problems with various radiators (with TRVs) not heating up ever since the system was installed two and a half years ago.

Heating engineer replaced valves on faulty radiators last summer because some of the radiators were belting out heat constantly through the summer even when set to zero (when we just wanted the towel rails to be heated). He also reattached metal spacer for full connection on the valves.

Problem recurred as soon as we started using the heating regularly again in late autumn. At this point we paid for the system to be drained and new Honeywell TRVs to be fitted to all radiators. (The heating engineer who did this job bemoaned TRVs and said that we should just get them all removed and have a wall thermostat installed. His company told him to do the job in the end.)

This worked for three months, but we went away for a four day break and when we returned the radiator in our bedroom (furthest from boiler) had stopped working. Since then this radiator has mostly not worked, but occasionally starts heating up again.

Called the heating engineer again (same guy who drained the system down 3 months ago) today. He said that if the pressure is below one isobar then there is probably air in the pipes and the system will need to be drained. This is clearly expensive, and not something I am happy to have done every three months!

Any ideas?! My cynical side feels like I'm being taken for a ride by the property care company, but don't really have the knowledge to know if I'm right.

 

[Slugbabydotcom]

He said that if the pressure is below one isobar then there is probably air in the pipes and the system will need to be drained.

One isobar LOL Has someone been watching the weather forecasts too much lately
If the pressure is below ONE BAR then it needs topping up. Instructions in the FAQ's

About Rads not coming on.

1a Trvs are monodirectional and fitted the wrong way round
OR
1b They are sticking. During the summer set them to the max setting when the heating is not being used. There are posts about freeing stuck TRV's on this site
1c Cheap TRV's always cause problems. Better quality bi-directional TRV's do what they are supposed a better job and eventually pay for themselves

2a System could have sludge in it and a magnaclean or boiler buddy maybe needed. IF THE SYSTEM IS DIRTY a flush or powerflush may be needed as well. You need a heating engineer who knows the difference between a bar and an isobar to advise you further on that one.
2b There could be a blocked pipe. Its rare that a powerflush can clear a blockage, so pipes may have to be removed. A magnet can be used to give away the locations of blocked areas of pipework

3 A pump could be on its way out

4. System may need balancing


EDIT:-

Since then this radiator has mostly not worked, but occasionally starts heating up again.

I reckon you may not understand how TRVs work.
They stay OFF until the room gets below a set temperature and then come ON until the room is at the required temp.
It is not unusual for a rad to be off when others are on. This is just the TRV doing its job.
Read the TRV instructions because there is other stuff you need to know such as how to avoid creating a micro-climate in the valve sensor area