Confused, not dazed but definitely confused.

[dilalio]

Have you checked the bypass? Auto or manual? You want to make sure flow is NOT going via that when you focus pump on blocked rad(s) so this will need to be closed up during process but monitored as heat needs to go somewhere and you're trying to "encourage" flow to take the more resistant path (ie blocked system).

 

[WanderOverYonder]

I haven't looked at the bypass (mainly because it's in a tiny crawl space behind the hot water cylinder and I am a little on the large side for it - but will try and squeeze in). What setting should I have it on before I start to isolate each cold rad (or is it ALL rads I need to do?)

I totally get the flushing machine being primum optionem, however at nearly £400 this close to Christmas, I would prefer to exhaust other options first.
Appreciate all the advice, if I can solve this and have a happy wife, that can only equal happy life

 

[dilalio]

If its a manual bypass then crank it down when trying to send flow to individual rads.

You only need to do the cold ones first, but good practice to then go on and do the lot.

You'll have to monitor the bypass as boiler may start to lock out if heat doesn't get away from it... You just want the focused flow not to nip down the bypass route.

It is a balancing act but it's something you can fart about with as it's a time overhead rather than any cost for parts etc.

 

[WanderOverYonder]

So wee update. Not sure what to make of it.

Worst offending rad was the 300 x 1100 in the bedroom. Only ever got "warm". I isolated all of the other rads and left that one for 15 minutes and it got hot. Not burning but hotter than it's ever been.

So I set about draining it and disconnecting it. Once removed I opened the lockshield valve, water flowed out in a steady stream and within a minute or so hot water was freely flowing. From the TRV side the water was scolding.

Whilst I had the rad off, I took it outside and hosepipe flushed it, loads of black crap came out, gave it a bash with a rubber mallet and more came out.

I have reconnected it, filled and bled it so just waiting to see the result before I move on to the next.

Is it a good sign for that one that water flowed from the lockshield end and got hot whilst doing so? Does that rule out a sludged/blocked outlet pipe on that one?

Cheers (off for a cuppa now before the next one)

 

[dilalio]

Well. Its a good sign that you got some heat through it and a load of crap. You could always link the TRV valve and lockshield with a bit of pipe to ensure you get heat flowing across, whilst rad is off, but it does sound as if sludged up rads are the issue.

 

[WanderOverYonder]

Update on this and still issues but now different issues.

Had no heating for a day on Thursday after it all seemed to go pete tong. So plumber came out Friday. He deemed there was circulation, albeit poor, and put x400 in through the kitchen rad. It has definitely circulated as its in all of the rads now (found when bleeding).
He did diagnose that the pump was not working well and replaced it (Grundfos UPS replaced with UPS2).
Now it seems there is air in the system constantly and the expansion pipe in the attic seems to be hissing on and off with surges of bubbling coming out in the F&E tank.
3 upstairs rads are hot, 2nd from boiler needs bled every hour but the others are fine. Downstairs get warm but not hot, so not a lot of change there.

I am at the end of my patience with it now considering how cold its just gotten.

Any suggestions?

 

[oldbuffer]

Blocked cold feed? Test cold feed pipe from F&E tank to where it joins system (should be near pump or air separator) with a magnet. If sticks, likely to be blocked. Solution is cut out blocked part(s) and replace with new pipework.

 

[WanderOverYonder]

Blocked cold feed? Test cold feed pipe from F&E tank to where it joins system (should be near pump or air separator) with a magnet. If sticks, likely to be blocked. Solution is cut out blocked part(s) and replace with new pipework.

Thanks, if it were blocked would the F&E tank drain fully when the draincock is opened? How would the water get out if there is a blockage?

 

[oldbuffer]

It would probably drain, but very slowly. Blockage doesn't have to be complete, but enough to be too slow to make up primary circuit water losses in a timely manner.

 

[WanderOverYonder]

I only ask as the pressure at the draincock is quite high when it's drained and empties quite quickly. I will try and find a magnet (not something I tend to have around) and check the joint pipe.

 

[oldbuffer]

If it drains fairly quickly with no radiator bleed valves open and no air inlet other than the F&E, then its probably not the cold feed.

 

[WanderOverYonder]

Ok so magnet didn't seem to stick to any pipes around the pump area.

And it gets more weird. I shut the hot water off and shut off all of the rads except the one that needs bled all the time. Then bled it fully until it was hot. Then let it run on its own for 30 minutes. No air issue. Then I opened the other rads one at a time every 20 minutes to let them heat up and run and it all worked. Until I opened the bathroom towel rail and almost straight away the problem rad started losing heat and clearly needed bled.

Once I switched the hot water back on the problem got worse and the rads downstairs that were hot cooled down to just warm again. I am losing with will with this now.