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Downstairs radiators aren't heating up properly. I can get them hot one at a time by shutting everything else off and opening them right up, although there is more than a hint of sludginess about the way they heat up.
The central heating runs for a bit, but turns itself off well before the rads downstairs are starting to get hot.
I've had the pump head off and it seems to be moving freely - bit of blackness around but not completely grimed up.
Does that sound like the pump is on the way out, or should I go to the bother of hosing out the downstairs rads before spending over £100 on a new pump head?
Sludginess you say....
Could it be.. full of sludge?
I'd certainly want to empty out a rad or two before shelling out for a new pump. There are some good vids on https://www.youtube.com/channel/UCwF8vOEatNvJUiXXJtDx-zA if you've never tried it before.
J
I'd try bleeding the air out of the rads first.
All the rads are bled - they are cooler at the bottom, which is either sludge or just lack of flow, or a bit of both. The deterioration in temps has been pretty sudden though (I think).
Pump is a Grundfos, and about 8/9 years old.
If it's warming and then turning itself off I'd be more concerned about gunk in the heat exchanger .
Maybe try isolating upstairs rads and getting downstairs warm....
I had a lot of grief before Christmas with gunk in primary &secondary heat exchangers.in a combi .
Had to flush out system,remove and clean heat exchangers,since then all has been toasty.
If it's warming and then turning itself off I'd be more concerned about gunk in the heat exchanger .
Excuse my ignorance of how boilers work - so that means that heated water isn't passing away from the exchanger quickly enough and tripping a sensor telling it that the system is at the right temperature?
Could that be a pump pressure issue too?
Could be many things
- limescale in heat exchanger
- sludge in head exchanger
- air lock in system
- air in rads
- unbalanced rads with one shorting out the rest
- poor pump pressure
Yes the boiler thinks the water is very hot and stops heating it. If there was a pressure issue there's more than likely an alarm/indicator to tell you.
Very confusing/frustrating because it can be ,diverter valve,heat exchanger or pump.
But if the pump head is moving ok ,then less likely ....
Cheers guys. Just rebalancing the rads now, there were a couple out of kilter, we'll see if that makes a difference.
Lock diverter open to check that next?
Lock diverter open to check that next?
Can do, they normally just fail closed so no rads would heat.
It's just a shame that I can't tell it's the pump without replacing the pump!
The bloody system has just suddenly started working properly again. Which is almost as frustrating because I don't know what I did to make it happen!
You re-balanced the radiators!
Nah. Didn't improve til well after that. I'm suspecting there was a mystery airlock somewhere that has been dealt with. Or God is just playing with me.
Cool ,maybe put a magnetic filter on the return central heating leg.
Or leave it and keep fingers crossed .
On a couple of occasions mine heated up after flushing , but then failed to come on next morning .. 🙁
The plot thickens. It reverted to type and it seems to be something to do with the 2-port heating valve - sticking perhaps. It being only partially open would explain some of the symptoms. Removed the synchron motor and opened it using the lever.
However, now the CH seems reluctant to call for heat. Do I need the synchron motor wired in in some way to make that happen?
I thought my valve etc was faulty, turns out the boiler was totally knackered and just couldn't pruduce enough hot water for the system.....since the new Combi every single rad is super hot......they were last like that about 25 years ago!
If the valve is forced open and the boiler is on, then all the rads are getting hot enough. It's just decided it doesn't like me mucking with the valve wiring I think and has decided to not to play.
Sorted now. Loose internal connection on the synchron was making the motor stop and start. New synchron has sorted it out, toasty warm rads. 🙂
Would've been nice to think of checking that before taking the boiler apart and rebalancing the rads, but hey ho.
What's a synchron?
It's the little motor that drives the motorised 2-way or 3-way valves that turn the hot water/heating section of your system on or off as required.
. I'm suspecting there was a mystery airlock somewhere that has been dealt with.
I get this every time I drain the system, upstairs heats fine and downstairs gets no heat for several hours until the airlock passes and then it all works fine.