Boiler overheat tripping

[kris]

Defo a circulation problem of some kind. If pumps fine then somethings causing the heated water not to move .

 

[Gary59]

Had the same problem more or less 2 weeks ago, removed blockage in pipe work by connecting garden hose to CH return pipe, another hose to flow pipe to eject water away and back flushing each rad in turn while rest screwed down. Lot of crud removed and heating worked fine after.

Make sure it is not the pump first thou.

 

[Reman]

.

b. If possible, remove actuator head from 3 port valve. See if spindle can be turned easily, but don't forget they are only 15 to 20 degrees of movement open to closed. If doesn't turn easily, replace valve (probably drain down required).
icity and go carefully with the water side ready to deal with unexpected leakages.

I want ready to get wet tonight so I'll look at the pump I'm the morning.
I did pull the 2 way valve apart though.
`Thanks for the 15-20 deg advice. If i'd not seen that I'd probably thought it jammed and unjammed it very roughly and broke it!
From what i can see though, there is no OFF its either A or B so even if this was jammed it would not be "shut", it will still let water pass one way or the other so should not cause the problem I have?
I'll poke at the pump in the morning

 

[Reman]

Looking further at the valve spec its actually 3 way (4073A) I believe so you can have , water, heating or both. With this in mind and the fact that the pipework is getting plenty hot on both outlets I've convinced myself for now that the chance of it being totally blocked in any position is slim, therefore I'm putting it back together for now. I also ran the boiler for a considerable time with it on its lowest temp setting before bed, without it tripping the overheat, so next stop the pump I think?

 

[Reman]

We were all in the right area, but I needed to be sure! Apart from anything else the pump was a pig to get at, due to having had built in wardrobes built around the old airing cupboard location, so needed to be sure before I got on it as I'm not very bendy!
Pump bought stripped the head unit off to save disturbing the piping, re-wired, and of it jolly well went

Good work and thanks to the to the UKP collective
:coolgleamA:

 

[Subby]

I've had a couple of older gloworms overheating and a powerflush has sorted the problem. maybe the system would benefit from a bottle of x800 for a day or two then a full cold and then hot flush with all zone valves hooked open, and the tank in the attic cleaned thoroughly with sponges, buckets, wetvac etc, and re filled with a decent inhibitor x100 etc

 

[Reman]

Well theres an update to this, it worked perfect on plain water for about 2 weeks ,so I thought I'd finish the job with a flush of cleaner (as suggested) to remove any other issues mentioned before I put it all back together for the winter.
So I drained it down, dropped in the F3 cleaner and ran it for a few days, but found that occasionally it was tripping the overheat on first timed switch on. Reset then ran OK, I guessed it had perhaps got a bit of air in the boiler circuit. But put up with it for the few days.
Drained it down, refilled for the first of 2 rinses. First rinse worked perfect for a couple of days, second rince for last two days its been tripping from cold start.
I can only guess that it needs a super bleed, so would not worry till its got inhibiter in it and bleed super thoroughly.
Anyway thats where we are BUT. In the process of doing this the drain above the boiler has got increasingly leaky, having had to shut it tighter and tighter to keep it from dripping. So tonight I drained it and to put the inhibitor in and during filling the train leaks and I can't stop it!!
So I've had to abort and drain down again and I'm now scratching my head wondering how I get out of this one!
Biggest problem is limited access without tearing the kitchen apart as you should a see from the pictures. Only by wafting my phone under the coving could I get this shot.
So the question is, can you identify the options from the fittings used?
I wondered if I could cut off this drain and compression drain, but I'm not sure that the size is right or there is enough shank to do that? Thanks in advance, I'm seriously in the dog house!!

 

[jtsplumbing]

Just buy a new drain off cock and replace innards or just replace washer

 

[gassafe]

As above.. It looks relatively modern, so should only need new innards from replacement valve... Just make sure the washer comes out whole & has a good seating face before fitting the new one!

Sometimes they seal up once ther warm as the runner reseats... I would try it on hot water only & crank the stat up!!

 

[Reman]

Thank guys , been on the desk job too long!
Washers fitted job jobbed.
Tonights mare is getting the boiler to run without tripping the super over heat theres obviously no water got to it and the pump is pulsing (yes bled that) so I'm in the middle of another drain and re-fill again. I think i must have been really mean to someone recently!