Upstairs hot, downstairs cold

[RoyalCrabs]

Hello, as per title but I have run through the typical proceedure of bleeding, balancing etc but just wondering if the next route is saying its an intermittent pump issue or zone valve ?


System is a gravity fed oil burner 3 port v feeding the upstairs rads, but all the downstairs rads are fed from the upstairs circuit.
If I close all the upstairs rads, then all 3 downstairs rads get piping hot, if I try to re open the others (even barely) the next day they go stone cold again while the upstairs hot. It appears they do have a clear flow when I shut off all the upstairs rads so I do not believe it to be sludge.

The controls are ancient , some push button jobbie thats being changed eventually

I'm changing all the TRV's for new ones this week so I'll run some cleaner through and see if it does it again.. Just want to be prepared / plan ahead, its family but its a trek over there so cant be bothered with back and forth..

I dont think the problem lies in the old TRV's though as they do work they just are crusty and look terrible, I could be wrong though.

Any thoughts (experience) welcome!

 

[jonnyswamp]

Change the pump while you're at it, sounds tired

 

[RoyalCrabs]

It cant help right? That being said, at some (effing) point someone built a set of cabinets around the pump / flow + ret side of the boiler, leaving only enough access to bleed the pump. Fantastic that.

 

[RoyalCrabs]

Thought Id reiterate that when I shut off the upstairs rads, the downstairs do literally get piping within a few mins like they should do on full whack , can't be sludge ?

 

[hammers4spanner]

pump

 

[Best]

I agree that it could be circulating pump. It doesn't happen often, but sometimes you get a pump with age that seems unable to do the furthest rads or the drops to downstairs rads.
Or the pump impeller or body is blocked a bit with magnetite.
Make sure the system is balanced well also.

 

[Tjdservices]

I'd go with pump as well

 

[RoyalCrabs]

Thank you,
I'm starting to get the feeling also. The other day I had the boiler on for a good few minutes, the feed to the pump was hot and the other side warm, then it kicked in, I was hesitant to say straight up its the pump as the controls have apparently been dicky..

I have balanced the rads to the point where the upstairs ones are barely open and it sorts out the issue while im there but sods law the next day, down stairs dead cold again..

 

[AWheating]

pumpty dumty.

 

[WHPES]

Pump (sounds like you need a joiner too). Stick in a modern A rated pump like the Grundfos Alpha, will save you a bit on electricity costs (these pumps actually do consume quite a bit of electricity as they run more or less constantly). Change the pump valves at the same time, and make sure an automatic bypass valve is present between the pipe directly after the pump and the boiler return. Flushing the system goes without saying.