Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Andy H]

Potterton Profile conventional boiler, with hot water tank next to it and feed and expansion tank in the loft.

The boiler seems to run fine for a while and all the radiators get hot, but then it will give a big gurgle and shuts down.    This also happens when heating water, but the gurgle is worse and the boiler shuts down more often!  Sounds like there is a lot of air in the pipes around the boiler and hot water tank. 

I've bled all the rads and they're fine, I've opened the bleed valve above the 3 way valve and that was fine, and I've checked the feed and expansion tank and that's OK, the pump appears to be running OK, and apart from draining down the system and refilling it I'm out of ideas! 

Might there be an airlock somewhere in the pipes around the boiler and hot water tank? 

Any advice appreciated please!  I'm bleddy freezing!!   

TIA! 

Sounds to me as though the pump is sticking - running OK when cold but seizing when it gets hot. In hot water mode the system gets hotter quicker hence the shorter intervals between gurgles.

The primary cause of pumps sticking is a build up of magnetite (black sludge), a magnetic form of iron oxide that gets attracted to the magnetic field in the pump motor.

If the pump is running at all then you should be able to unscrew the bleed screw (with a bowl under it) and watch a trickle of black sludge dribble out followed by cleaner water as the magnetite gets washed out.

[Sir Tigger KC]

Very common for the rubber washer in a drain cock to weld itself in place - you might have to pull the guts out with a pair of pliers or mole/vice grips to get things flowing.

I poked a bit of wire in it and managed to get it dribbling but as soon as I pulled the wire out it stopped again.    I guess it's just perseverance and willingness to get wet and make a mess! 

Sounds to me as though the pump is sticking - running OK when cold but seizing when it gets hot. In hot water mode the system gets hotter quicker hence the shorter intervals between gurgles.

The primary cause of pumps sticking is a build up of magnetite (black sludge), a magnetic form of iron oxide that gets attracted to the magnetic field in the pump motor.

If the pump is running at all then you should be able to unscrew the bleed screw (with a bowl under it) and watch a trickle of black sludge dribble out followed by cleaner water as the magnetite gets washed out.

I've removed the bleed screw Andy and all I've had is clean water dribbling out. 

It's been a frustrating day! 

[TD]

So it looks as though I've got big problems here.   

I can't drain the system!  As I write I have 2 drain cocks open with hoses going outside with nothing coming out!

If I open bleed valves on the radiators water comes out and I've tried sucking/blowing down the hoses with no success.  It looks like it's clogged up solid...

What happens when the header tank is left open to fill the system.... I think probably nothing will happen...I think the reason nothing is coming out when your draining the system....is theres little water in it, apart from whats in the rads....so if buggar all comes out of the drain pipes, when the header tank is left open to fill the system...it certainly points to a blocked cold water feed 

[Sir Tigger KC]

I think Andy's right in that the draincock washers have welded themselves in place, as when I've poked them water comes out and there's pressure there too! 

I don't think it's gunk blocking the draincocks either as I tried back flushing them with the hose, but I think I was just pressing the washer more firmly in place! 

Also I managed to get about half a bucket out while poking the draincocks with a piece of wire and the level in the header tank went down, so that's a good sign as well! 

[Shackeng]

I think Andy's right in that the draincock washers have welded themselves in place, as when I've poked them water comes out and there's pressure there too! 

I don't think it's gunk blocking the draincocks either as I tried back flushing them with the hose, but I think I was just pressing the washer more firmly in place! 

Also I managed to get about half a bucket out while poking the draincocks with a piece of wire and the level in the header tank went down, so that's a good sign as well! 

These washers are replaceable, just remove the whole screw to do so. Plumbers usually use the cheaper drain cocks with no locking ring, but in each case the washers are replaceable.

[Sir Tigger KC]

I think Andy's right in that the draincock washers have welded themselves in place, as when I've poked them water comes out and there's pressure there too! 

I don't think it's gunk blocking the draincocks either as I tried back flushing them with the hose, but I think I was just pressing the washer more firmly in place! 

Also I managed to get about half a bucket out while poking the draincocks with a piece of wire and the level in the header tank went down, so that's a good sign as well! 

These washers are replaceable, just remove the whole screw to do so. Plumbers usually use the cheaper drain cocks with no locking ring, but in each case the washers are replaceable.

Yes I will replace the washers, but I'd rather remove the water first though!   

[Shackeng]

I think Andy's right in that the draincock washers have welded themselves in place, as when I've poked them water comes out and there's pressure there too! 

I don't think it's gunk blocking the draincocks either as I tried back flushing them with the hose, but I think I was just pressing the washer more firmly in place! 

Also I managed to get about half a bucket out while poking the draincocks with a piece of wire and the level in the header tank went down, so that's a good sign as well! 

These washers are replaceable, just remove the whole screw to do so. Plumbers usually use the cheaper drain cocks with no locking ring, but in each case the washers are replaceable.

Yes I will replace the washers, but I'd rather remove the water first though!   

Ah sorry, I thought you were suggesting that the washers were blocking the outlet.

[Sir Tigger KC]

I think Andy's right in that the draincock washers have welded themselves in place, as when I've poked them water comes out and there's pressure there too! 

I don't think it's gunk blocking the draincocks either as I tried back flushing them with the hose, but I think I was just pressing the washer more firmly in place! 

Also I managed to get about half a bucket out while poking the draincocks with a piece of wire and the level in the header tank went down, so that's a good sign as well! 

These washers are replaceable, just remove the whole screw to do so. Plumbers usually use the cheaper drain cocks with no locking ring, but in each case the washers are replaceable.

Yes I will replace the washers, but I'd rather remove the water first though!   

Ah sorry, I thought you were suggesting that the washers were blocking the outlet.

Yes I think they are, but hopefully I can dislodge them enough to drain down the system without making too much mess. 

[Andy H]

I've removed the bleed screw Andy and all I've had is clean water dribbling out. 

It's been a frustrating day! 

I am wondering if the water side of the system is actually OK

In my last house I had a Potterton Prima boiler and Y plan controls. In 15 years the circuit board in the boiler failed once but the 3 port valve actuator failed 3 times.

[Kevin Wood]

I am wondering if the water side of the system is actually OK

In my last house I had a Potterton Prima boiler and Y plan controls. In 15 years the circuit board in the boiler failed once but the 3 port valve actuator failed 3 times.

PCBs are poorly made on these. Replace the caps with 105C rated types and resolder all the mains connections and they are fine thereafter.

[Sir Tigger KC]

I am wondering if the water side of the system is actually OK

In my last house I had a Potterton Prima boiler and Y plan controls. In 15 years the circuit board in the boiler failed once but the 3 port valve actuator failed 3 times.

PCBs are poorly made on these. Replace the caps with 105C rated types and resolder all the mains connections and they are fine thereafter.

Yes this one's had 3 PCB's and a 3 way valve, which I don't think is bad for a 23 year old system. 

[Marks DTM Calib]

I am wondering if the water side of the system is actually OK

In my last house I had a Potterton Prima boiler and Y plan controls. In 15 years the circuit board in the boiler failed once but the 3 port valve actuator failed 3 times.

PCBs are poorly made on these. Replace the caps with 105C rated types and resolder all the mains connections and they are fine thereafter.

Yes this one's had 3 PCB's and a 3 way valve, which I don't think is bad for a 23 year old system. 

You never need to replace the PCB on these, a bit of soldering and 80p of capacitors and they are good for another 8-10 years

[Kevin Wood]

Yes this one's had 3 PCB's and a 3 way valve, which I don't think is bad for a 23 year old system. 

Didn't I offer to fix a PCB for you once? Offer still stands next time I'm in Salwayash (which might well be into the new year by now).

[Sir Tigger KC]

Yes this one's had 3 PCB's and a 3 way valve, which I don't think is bad for a 23 year old system. 

Didn't I offer to fix a PCB for you once? Offer still stands next time I'm in Salwayash (which might well be into the new year by now).

Yes you did! I forgot about that.  Thanks! 

[TD]

I am wondering if the water side of the system is actually OK

In my last house I had a Potterton Prima boiler and Y plan controls. In 15 years the circuit board in the boiler failed once but the 3 port valve actuator failed 3 times.

PCBs are poorly made on these. Replace the caps with 105C rated types and resolder all the mains connections and they are fine thereafter.

Yes this one's had 3 PCB's and a 3 way valve, which I don't think is bad for a 23 year old system. 

Bout time you bought a new boiler then.....a quick google on your boiler shows its only about 70% efficient 
But I guess it depends how long you intend to live in the property 

Have you sorted the problem?