Radiators hot upstairs and cold downstairs

[diselsamm]

I've a pressurised CH system with a combination vented cylinder.
I live in a two story house with 4 radiators upstairs and 4 downstairs. I recently had the CH pressurised and the cylinder also was replaced.
The problems is that the radiators upstairs are getting nice hot but the ones downstairs are not. The pump is working as I can hear it. I bled the radiators and left the lockshiled of the radiators upstairs a quarter closed and the TRVs are at 3. The lockshields for the radiators downstairs are fully open and the TRVs are at maximum. The boiler is Worcester 18ri and is downstairs.
Any advise on what I can try to troubleshoot the problem will be greatly appreciated.

 

[ShaunCorbs]

Pump weak I would say

 

[diselsamm]

Hi Shaun
It is a Grundfos UPS3 currently set at speed 2, installed February this year. What speed setting the pump should be at?
Thanks

 

[ShaunCorbs]

Tbh you should be fine then and speed 2 should be more than enough for 8 rads if you close all the rads upstairs do downstairs heat up ?

 

[diselsamm]

Two of the radiators downstairs started warming up. One of two that did not warm up I felt had a very stiff lockshield when I was trying to balance, but I manage to leave it fully open (the lockshield). The furthest one did not warm up.

Currently my thermostat is upstairs and the heating basically is not running at the moment. Should I move it downstairs and give the system the chance to run?

All this started after the CH side was pressurised but might be coincidence. After we had it pressurised we were losing pressure which was diagnosed to ruptured cylinder coil, hence the cylinder was replaced. Now the system is back up but trying to resolve the cold radiators story.

 

[John.g]

Was the system chemically cleaned?
What is the system pressure?

Is the pump set as indicated for speed 2, solid green + solid yellow, LEDs?

 

[diselsamm]

Thank you John
As we speak the system is running a Sentinel x400 for a few days now (since Thursday when we had the new cylinder installed). I have a Magnaclean as well since August which I've been cleaning periodically. I was planning to clean in a week time and add more Sentinel.

The system pressure is around 1.3-1.4 Bar.

Yes, set as at CC II with the led lights accordingly. I tried PP 2, which made the pump very quiet (which I liked) but I am not sure that is a correct setting to use at all?

 

[John.g]

Are you picking up much in the Magnaclean?

CC2 setting should be more than enough, its 5.2M, CC3 at 6.4M will give you ~ 13% more flow but don't think thats your problem. PP2 is pretty useless.

 

[diselsamm]

Not collecting really much (black) but that was with the HW only back in August. The cylinder was installed only on Thursday... I will check in a week time, or having the cleaner ran now for 2-3 days I can already check and clean?

 

[John.g]

I would check and clean it especially if its circulating the rads now, is there any other "strainer" in the Magnaclean to trap any other non magnetic material.

 

[diselsamm]

I will check the filter. It is a MagnaClean Pro2 and I believe it has a pocket/strainer for limescale...

 

[diselsamm]

Just checked it, it had a small accumulation of sludge and was certainly not getting blocked.

 

[John.g]

I know it's unlikely but there has been a fair share of dud UPS3s if your old pump is still around maybe worth re installing it as a test.

 

[diselsamm]

The old one is long gone and was not working properly. For what I can tell the UPS3 seems to be working but what am I looking for to say for sure?

 

[John.g]

Most A rated pumps display the power in watts, unfortunately the UPS3 does not, but if you have a energy monitor you might be able to see the pump power in watts, otherwise maybe one of those plug in ones and connect the pump lead in to it temporarily, you should be getting betwwen 35 and 40 watts IMO on CC2.
Also, ensure that the pump is installed pumping in the correct direction.

The flow/return boiler temps, if displayed will give a clue as well re circulation rate.

 

[ShaunCorbs]

Two of the radiators downstairs started warming up. One of two that did not warm up I felt had a very stiff lockshield when I was trying to balance, but I manage to leave it fully open (the lockshield). The furthest one did not warm up.

Currently my thermostat is upstairs and the heating basically is not running at the moment. Should I move it downstairs and give the system the chance to run?

All this started after the CH side was pressurised but might be coincidence. After we had it pressurised we were losing pressure which was diagnosed to ruptured cylinder coil, hence the cylinder was replaced. Now the system is back up but trying to resolve the cold radiators story.

I would if you could and just run downstairs eg shut all the trvs upstairs if you can

 

[diselsamm]

Hi Shaun, I've tried this and the result was two radiators started to be lukewarm.
I wonder whether there is a good heating engineer in East Devon?

 

[John.g]

Maybe worth a try again with pump on CC3, shut all u/stairs again and pump through each rad in turn downstairs with the others shut off, there may be air still trapped somewhere, if you dont want excessive gas? boiler cycling while doing this you could switch it off and manually latch open any relevant zone valves and give the pump a independent power supply.
Are the downstairs rads separately zoned?.

Another clue to pump condition is to watch the boiler pressure when the pump starts and watch for rise in pressure, but depends on where the E.vessel is installed.

Is there a automatic bypass valve (ABV) installed?.

 

[diselsamm]

I think the problem is a seized lockshield. Now my problem changed: it is dripping. Ah, Sunday morning joys...

 

[John.g]

If from the gland, tighten gland nut?

 

[diselsamm]

I think it is from the gland/stem and tried to tighten it up, including all other nuts however it is still seeping... I think the whole valve will have to be replaced. Problem is I am having a difficulty finding a good heating engineer/plumber. Been a huge struggle.

 

[Ben-gee]

Whereabouts are you?
Nearest town/village?

 

[diselsamm]

Hi Ben-gee. East Devon. Thanks.