2 radiator related questions ...

[steved101]

Hi

2 quick questions. My friend has a faulty TRV and wants it sorted - I know it's hot!! but she has the heating on each morning for an hour to take the chill off!

I have replaced rad valve's before, but on open-vented systems. She lives in a flat and has a combi. Is it the same procedure but instead of shutting off the F and E to drain the system to I need to just turn off the main stopcock ?

Also can I please ask what are the signs/reasons for a blocked cold feed (to an open vented system-primary circuit)? I am not a qualified plumber, I am learning plumbing and am doing some jobs for friends when I can. My cosuin lives in a 3 bed house and says his pmp is making a squaling noise and I believe he has a blockage in his cold feed/neutral point. Am I right? How can I be more sure .. I am going round to look at it tomorrow evening, but I know for a fact he has a Grundfos circulating pump, fully pumped system with a Honeywell 3-port mid positon motorized valve.

Any kind of help would be useful?

Thanks all.

 

[gasmataz]

combi is filled by external or internal filiing loops no need to turn mains of just fill system back up when done to required pressure(1-1.5 bar)

Dont know why you would think it was a blockage on a pipe due to noise i would start with the obvious and bleed the pump. hope this helps a little and feel free to update your situation for further diagnosis.

 

[steved101]

thanks for the tips. i have never drained a combi/sealed system before. with an open vented - you shut off the supply to the f & e and drain through a drain valve at the lowest point.

what do you shut off to drain a combi/sealed system? thank you for your time.

about the noisy pump-i was thinking maybe possibly the cold feed was blocked, causing water to be pumped out of the vent and thus making the pump noisy due to the blockage somewhere in the cold feed / where it joins the system, the neutral point?

 

[gasmataz]

you dont need to shut anything off on combi it's already off you just fill system back up from filling loop when finished. If you want to make sure the cold feed isnt blocked drain a little from system and if f&e tanks runs then you know it's not blocked. i would say there is are in the system just bleed it from pump. might even need to change pump speed.

 

[steved101]

thanks for the tip there. on my way to have a look soon! could the prob possibly be a blocked vent?! he said water at times shoots out of the vent ... why would this be? thats why i was thinking it may be a blocked cold feed.

 

[gasmataz]

i doubt that would be your problem i can honestly say ive only ever had a hand full of blocked cold feeds and it was always spotted on refill of system not from water coming out of vent. by this im assuming you mean to do with the positive/negative side of pump being effected? Water coming out of vent is normally from air in system and from overheating. bleed pump and take it from there if i was you. If water coming out of vent was common then look into it more if just a one off forget about it.

 

[steved101]

hmm interesting, so air in the system is causing a bit of water out of the vent somehow?! as it is not/was not a thermostat fault. bleeding the pump should cure this hopefully ...