Should header tank get hot?

[PaulAH]

Conventional open-vented CH system. Within half an hour or so of the system firing up, the header tank in the loft gets hot to the point of steaming. Haven't yet stood there long enough to see whether it's regurgitating up the downpipe or being heated, cappucino-style, by steam from the vent.

Is this normal?

 

[Nige F]

NO yet another pipework cock up, allegedly

 

[HandyJon]

Is your boiler thermostat working? It could be that the boiler isn't being told to switch off so it keeps on heating up the water till the heat rises up the vent pipe.

 

[oilman]

When you installed your boiler, did you do any work on the pipework from the header tank?

 

[PaulAH]

It sure is. No obvious problems in that department. I'm wondering if the pump (Grundfoss) should be turned up to max speed (it's currently on 2/3) to help heat dissipation and the temp turned down a little on the boiler. Or does the condition suggest there is something more fundamentally wrong?

 

[PaulAH]

Oops - we crossed. No work at all was done on the header tank side.

 

[oilman]

It suggests something fundamental. You need to check water is able to flow down the feed and expansion pipe. Shut off the supply to the tank, and check you can reduce the level in the tank by opening a drain cock. If you have a 22mm push fit stop end, putting this over the vent pipe will allow you to see if the flow rate is restricted.

 

[PaulAH]

The feed pipe is definitely OK - I drained the system only last week when fitting another motorised valve to provide an extra controlled zone. Tank emptied quickly. (This is not the cause; symptoms evident before this work).

 

[oilman]

Oh, another theory bites the dust. How long has it been doing it? What made you aware of it?

 

[PaulAH]

May be getting somewhere here. I've turned the Grundfoss up full (recommended?) and set the boiler stat to approx mid position. System's been running for an hour or more and header tank is no more than luke warm (reasonable? Won't there always be a bit of stray heat going up to it?).

Oilman - on the matter of history, it has been overheating for a long time. My son also reported kettling noises in the boiler recently, although I didn't have a chance to investigate. After draining last week, I also chucked in two full bottles of Fernox - it had only one before. Does this sound a good dose? Quite a large system with 20+ rads (as you know )

 

[oilman]

The kettling indicates the temperature is getting high, (sorry to state the obvious) it could be either the control stat is faulty, or the contact to the boiler is not good (try some copper slip in the thermostat pocket), or the heat input to the boiler is too high (could try a smaller nozzle, what size is it now?) or there is air in the top of the boiler.

Can you get a thermocouple to put in the thermostat pocket to check the stat? Is there a bleed nipple on the top of the boiler?

 

[PaulAH]

it could be either the control stat is faulty, or the contact to the boiler is not good (try some copper slip in the thermostat pocket)

Feels snug enough

could try a smaller nozzle, what size is it now?

Dunno. As supplied. I recall Boulter tech support saying it's at the lower end of the boiler's rated output range (that was when they were based in E Anglia and you could actually get through)

Is there a bleed nipple on the top of the boiler?

Bleed nipple? There's a bleedin' great blanking plug on top of the jacket with a square shaft for taking a spanner. Is that it?

Can you get a thermocouple to put in the thermostat pocket to check the stat?

Now you're teasing. What would a hack like me be doing with a thermocouple?

Could you just confirm whether a) Two bottles of Fernox inhibitor is reasonable and b) Setting the Grundfoss to 3 is sensible?

Thanks, as ever.

(Incidentally, have tried to get two different OFTEC engineers round to service the thing and neither called back).

 

[oilman]

How big were the bottles, but it's probably ok anyway. Did the system get powerflushed when you put the boiler in? Big plug is not bleed screw, though undo it and you will call it a bleedin' screw.

The pump should be set so you have 11 deg C between flow and return pipes on the boiler. What about a couple of clamp on thermometers if you can't get a thermocouple? Then you could check both bits at the same time and check the stat too.

Pain in bum with Worcester taking over Boulter, I don't get any guarantee referrals now, so I don't recommend Worcester boilers, that should make them quake .

 

[PaulAH]

4 litres each. Could have bought a new boiler at that price .

Might splash out on a pair of clamp-ons. If your OFTEC chums had bothered to get back, they could do it.

No, didn't powerflush but got an incredible amount of sh*t out of the pipework by hosing through for a couple of hours.

So you've found the same with the Boulter/Worcester takeover? I can't believe how rapidly a service can deteriorate in the cause of "modernisation". Used to get straight through to someone who knew what they were talking about. When I last called them, I got thrown off the phone menu three times, eventually getting through to some kid whose computer wasn't working and who seemed to know nothing even when it was.

 

[oilman]

4 litres each. Could have bought a new boiler at that price .

Use Kamco systemsafe next time, but just 2 litres.

[qoute]
Might splash out on a pair of clamp-ons. If your OFTEC chums had bothered to get back, they could do it.[/quote]

No chums of mine, I always ring back, mostly same day.

No, didn't powerflush but got an incredible amount of sh*t out of the pipework by hosing through for a couple of hours.

That's ok then.

So you've found the same with the Boulter/Worcester takeover? I can't believe how rapidly a service can deteriorate in the cause of "modernisation". Used to get straight through to someone who knew what they were talking about. When I last called them, I got thrown off the phone menu three times, eventually getting through to some kid whose computer wasn't working and who seemed to know nothing even when it was.

Well they don't care anymore, I know one of their salesmen, really gobby, but untrustworthy. I had a go at their technical manager after I found one of their man-in-a-van advised someone to just keep topping up the pressure on their combi. Turned out to be a shot expansion vessel, (safety problem) who cares?