Multizone Heating Issue

[new_DIYer]

Hi,

First post so here goes...

We moved in to a 5 bed house 7 months ago and it has a Glow worm 38CXI combo which has a multizone heating system. One thermostat downstairs and one upstairs.

The boiler has been serviced without issue but I am struggling with the heating.

I had a radiator upstairs which was cold at the bottom. I realised that the lock shield was almost closed so cracked it a bit and it became warm. No issues again. However, the living room radiator then became cool at the bottom.

So I decided to balance the system. Until yesterday everything was fine. Now however, one radiator upstairs (has no TRV) is cold at the bottom and the return pipe is very cool.

Am I doing something wrong? Have I balanced incorrectly with a multizone system? Or should I run some cleaner through for a week and see how this goes?

 

[sajeel]

have you checked for air and also pressure on you loop ?
it seems your setup is one boiler two zone valves and two thermostats ?

 

[new_DIYer]

Yep, no air at all and pressure is perfect. Stable at 1.0bar.

One boiler. Two zone valves and two thermostats. Valves work ok and can happily have downstairs or upstairs on.

 

[sajeel]

how many radiators upstairs and downstairs ?

 

[new_DIYer]

8 upstairs

6 downstairs

 

[sajeel]

If all the others are working fine then you are looking at faulty valves or a defective radiator, the easy way to test would be to drain down system or do you have a radiator the same size that you can swap with ? As the system is closed loop and the other radiators are all working fine ? or you could swap the valves from faulty radiator to another and see if problem occurs there, i suspect there is dirt trapped in one of the valves on both radiators.

 

[new_DIYer]

I don't have another radiator to swap with either of them.

Last night all were roasting hot so I think it may be time for a de sludge treatment then flush before inhibiting?

 

[sajeel]

I recommend a powerflush here is one company i know of http://www.powerflushing.co.uk/index.html
for 14 radiators will be £450 they will use machine and chemical to fully flush.
Do you have a filter on your water and central heating you need one like this fitted http://www.screwfix.com/p/flomasta-building-regulations-part-l-compliance-kit/4184g

Do post and let us know how you get on you can of course add part l kit first and then you can use tank to easily add cleaners and if that does not resolve a powerflush, a powerflush is good and will improve boiler effeciency.