Air Lock/Blocked Cold Feed Boiling Issues - HELP!

[fireblade]

very well described😀😀

 

[moogwai]

indeed....lol....will let you know how i get on with it.

 

[fireblade]

Cheers mate

 

[cr0ft]

Fuzzy,

Definitely not the TRV heads, I've replaced 7 and all are set to setting 5 (max) - new Comap heads and valves, that's how all this trouble started 🙂

There didn't seem to be any huge difference between the temperatures across the rads before it pumped over, not that I'm keen to turn it on again till I've found the fault - there was a LOT of boiling water flying into the tank.

Sparky,

It's an old floor standing boiler, when the boiler is off if I switch CH or HW on the timer, the relevant 2-way motorised valve opens and on comes the system pump (Grundfos). Water then begins circulating, including through the boiler (I can here it moving round). I don't want to turn the boiler on and leave it for a week or there will be nothing left of her upstairs ceiling or heating system probably!! Today was the first time I've been scared as a plumber, her central heating system was sounding like a steam engine!

Going to powerflush the system early next week, will see how I get on - I'm taking heart that it did actually run for 20 minutes today before problems started!

 

[fireblade]

wouldn't be the trvs shutting down with no bypass thats causing it to pump over

 

[cr0ft]

I thought of that too fireblade, but the upstairs towel rail doesn't have a TRV on it, so I guess that is the bypass. 🙁

 

[macplumb]

Have you opened the manual air vents ( if there is any) could be locked in the coil restricting flow so water is boiling off and blowing out of vent. Is the boiler triping out?

 

[Puddle]

sure we are not talking boiler thermostat gone and system over heating,boiling over?

 

[cr0ft]

Circulation around the system does seem to be there but it seems to be minimal even with the pump on setting 3. I do think the boiler thermostat is not working though, given how violent the overpumping/steam is into the header tank.

As she is an OAP, she's keen not to replace her heating system basically - the system is totally caked up with rubbish so I'm thinking a powerflush will do it no harm to try and get it working again. Perhaps this block-up has just revealed that the boiler thermostat is knackered too.

 

[fuzzy]

Circulation around the system does seem to be there but it seems to be minimal even with the pump on setting 3. I do think the boiler thermostat is not working though, given how violent the overpumping/steam is into the header tank.

As she is an OAP, she's keen not to replace her heating system basically - the system is totally caked up with rubbish so I'm thinking a powerflush will do it no harm to try and get it working again. Perhaps this block-up has just revealed that the boiler thermostat is knackered too.

i have had a problem with new TRV;s even when on 5 they shut down when the room is still cold? ive had to back off the nut holding the head. Just thought it may be something else to eliminate. id turn the pump down, if it is only going through 1 rad and set on 3 presuming the trvs are the prob it would pump over

did you check the bottom of the rads? how old are they? you could take 1 off and flush it through outside, check the amount of corrosion that comes out, thats a good indicator of the sludge that is in the system. Is the bathroom rad fully open?
Also, try running a hose pipe out of a lower drain with the system off but water keep filling it up, turn any motorised valves on and of, that should get rid of any air

 

[justlead1]

Hi Cold feeds are prone to corrosion as they are the nearest point to active water on cistern feed closed system. The movment of water due to expansion/contraction and evaporation can cause corrosion on beta brass fitting, valve etc. and is far more apparent on larger systems where iron barrel is used. Good Luck

 

[cr0ft]

Bathroom rad is very warm when system runs. Upstairs TRVs haven't been replaced (6 rads out of 13) and those TRVs were working ok before hence why I don't think TRVs is the issue tbh. I know for sure there is plenty of corrosion in the system, top and bottom - water in loft tank was brown with about 1 inch of sludge in the bottom of the tank. On closer inspection there is a sign of a pinhole leakage from one of the radiators.

I've resigned myself to powerflushing the system and have already told the customer that if it doesn't work then imo the system is at the end of it's working life.

Will see how the powerflush goes!

 

[fuzzy]

Bathroom rad is very warm when system runs. Upstairs TRVs haven't been replaced (6 rads out of 13) and those TRVs were working ok before hence why I don't think TRVs is the issue tbh. I know for sure there is plenty of corrosion in the system, top and bottom - water in loft tank was brown with about 1 inch of sludge in the bottom of the tank. On closer inspection there is a sign of a pinhole leakage from one of the radiators.

I've resigned myself to powerflushing the system and have already told the customer that if it doesn't work then imo the system is at the end of it's working life.

Will see how the powerflush goes!

i see, well with all youve said it appears to be sludge corrosion issue for sure, good luck

 

[cr0ft]

Thanks to all for their help with this. I powerflushed the system and cleaned the F/E tank out today and all is now working a treat, for now at least! A 27 year old system now seems to be working as good as new.

It amazed me that it worked for so long with so much rust and silt in it! The muck that came out of the powerflusher drain hose was incredible.

 

[fuzzy]

Thanks to all for their help with this. I powerflushed the system and cleaned the F/E tank out today and all is now working a treat, for now at least! A 27 year old system now seems to be working as good as new.

It amazed me that it worked for so long with so much rust and silt in it! The muck that came out of the powerflusher drain hose was incredible.

well done good result. It shows you it has been corroding for along time! all the rust comes from somewhere! Did you put treatment in?

 

[cr0ft]

Sure did. Risked an acid de-scaler clean too which seems to have sorted out the kettling in the boiler without exposing any unwanted leaks. 2 bottles of my local merchant's finest inhibitor in. Got the follow on sales, basically told her she needs to stop using whoever is servicing her heating and get me in to do it now 🙂 Luckily, I think she agrees..

 

[moogwai]

Sure did. Risked an acid de-scaler clean too which seems to have sorted out the kettling in the boiler without exposing any unwanted leaks. 2 bottles of my local merchant's finest inhibitor in. Got the follow on sales, basically told her she needs to stop using whoever is servicing her heating and get me in to do it now 🙂 Luckily, I think she agrees..

good stuff croft glad you got it sorted, there aren't many plumbers out there that wouldve done everything you have...most probably they would of said "not my problem"
you are like me...won't stop until i get it goin...in the long run you can only benefit from jobs like this one...word will get round.🙂