Hot water going in header tank

[Steve barber]

Hi can somebody tell me, I’m running an oil boiler 11 years old and a few months ago I noticed little green bits coming out the hot tap, and the hot water was taking longer to heat up, how ever the rads wear fine.
How ever I changed the pump because the old one was making a bit of noise.
That Warks fine then I noticed that it was staying on for 30 mins plus on the hot water side but it seemed fine in the rads.
After a bit of looking I went up the loft to see, when the water was on the boiler the pipe above the header tank had hot water coming out at some rate, so I turned the water off and just ran the rads and went for a look in the loft at the pipe again an it also had water coming out but not as fast, yes it was hot. Any ideas ?

 

[cross thread]

Pump speed to high

 

[Steve barber]

It’s not the pump speed. It’s on low and the stat on the boiler is on very low and the water still flows. Iv tried it fast and slow and it’s the same, so I think that’s not the right answer thanks

 

[Madrab]

Have a search on this forum on 'pumping over' and 'blocked feed and vent'. That will give you all the investigation pointers you need to diagnose what the potential problem could be.

Unfortunately I'm not getting into the ins and outs of what and where and what the possible reasons and remedies could be etc as there was a recent thread on this forum about exactly the same thing that just got wildly out of control over what's usually a relatively straightforward issue and solution and ended up running into pages and pages of sheer madness & silly nonsense

 

[opps]

* I am not a plumber *

Do you have an immersion heater tank that may have been left on by accident? I have worked in a few houses over the years where they were left on constant. The older heating elements could fail in the open position. The upshot was that boiling water was sent up to the header tank and from there in to the main water tank. After several deaths the regs were changed so that if a heating element fails, it fails in the closed position.

That said Madrab doesn't seem overly concerned so please feel free to disregard my post.

 

[Steve barber]

* I am not a plumber *

Do you have an immersion heater tank that may have been left on by accident? I have worked in a few houses over the years where they were left on constant. The older heating elements could fail in the open position. The upshot was that boiling water was sent up to the header tank and from there in to the main water tank. After several deaths the regs were changed so that if a heating element fails, it fails in the closed position.

That said Madrab doesn't seem overly concerned so please feel free to disregard my post.

Thanks but I can tell your not a plumber, I’m not a plumber as well but I am a tight ba….d so not the immersion has not been left on thanks any way any thoughts may help.

* I am not a plumber *

Do you have an immersion heater tank that may have been left on by accident? I have worked in a few houses over the years where they were left on constant. The older heating elements could fail in the open position. The upshot was that boiling water was sent up to the header tank and from there in to the main water tank. After several deaths the regs were changed so that if a heating element fails, it fails in the closed position.

That said Madrab doesn't seem overly concerned so please feel free to disregard my post.

 

[Madrab]

That said Madrab doesn't seem overly concerned so please feel free to disregard my post

It's not that I'm not overly concerned and of course it could be a runaway immersion heater but that would usually present itself in a different way, usually as an attic full of steam and a vent pipe that's releasing boiling water up, over and out the vent like a runaway kettle. That softens the plastic cistern and dumps boiling hot water down below so always good to point these things out in case the OP isn't sure.

The OP's description does point towards pumping over, which is usually a badly placed pump, too high a pump speed or a feed and vent restriction/blockage issue. They tend to show themselves especially when a new pump is installed. That and it heads into the Feed and expansion (header) tank that has maybe a couple of Litres of water at best so isn't as big a concern

 

[opps]

It's not that I'm not overly concerned and of course it could be a runaway immersion heater but that would usually present itself in a different way, usually as an attic full of steam and a vent pipe that's releasing boiling water up, over and out the vent like a runaway kettle. That softens the plastic cistern and dumps boiling hot water down below so always good to point these things out in case the OP isn't sure.

The OP's description does point towards pumping over, which is usually a badly placed pump, too high a pump speed or a feed and vent restriction/blockage issue. They tend to show themselves especially when a new pump is installed.

Thanks for the clarification. I only mentioned the immersion heater after having read about people sleeping in bed being killed by boiling water when the tank collapses. I just wanted the OP to be aware of it.

 

[Madrab]

Thanks for the clarification. I only mentioned the immersion heater after having read about people sleeping in bed being killed by boiling water when the tank collapses. I just wanted the OP to be aware of it.

Definitely, this is a DIY forum and no one should ever be discounted when sensibly contributing and drawing attention to any/all potentially dangerous situations, especially like the one you describe.

 

[Steve barber]

Fair comment

 

[opps]

Fair comment

No offence taken.

I recently worked in a house with a megaflow. I only noticed that the heating elements were on constantly after British Gas turned up to do some work on late Saturday. On Monday when I turned up, I immediately noticed that the plastic cover for the upper element was missing. I asked the customer why they were on, he shrugged. I turned both elements off and ordered a new cover.

 

[Madrab]

Fair comment

That wasn't directed towards you @Steve barber , just a response for @opps as to that what he suggested was certainly valid and that I wasn't discounting his comments either

 

[BlueLoo]

What pump was in and what pump did you replace it with?
What setting do you have it on?
The usual outcome of these threads is corrosion and crud in the system has built up so that the system grinds to a halt.

If you are handy, you can clean it quite well yourself.
If not, you can get a person in to do it for you.
Either way, it wouldn't do any harm and is preventative maintenance.

You may have some constrictions which are so bad the pipes need replacing. Sometimes the cleaning can sort that. Sometimes a stick is needed....

I like solutions that cure the illness, not the symptoms, so I'd clean the system 1st. remove rads, flush, clean head tank, push cleaner through the system for a while, etc.
Others like to treat the symptoms by fiddling with valves, balancing etc.

Get the system as is clean, then rebalance would be my thoughts.

Best of luck .

 

[Steve barber]

It was a Grunfos pump a red one and I replaced it with a Grunfos but is a modern one with some lights on it. £115 the new one was but the old one was £250. I thought that they are the same make but I did think that the quality may not be quite as good but I will give it a go.

 

[Madrab]

Can't really go wrong with Grunfos, they are pretty well made and a major player in the market. Apart from the noise your old pump was making, did you notice any deterioration in your system performance, were the rads not as hot, taking longer to warm up etc or was it just the hot water issue you were seeing?

The newer pumps are stronger than the old, especially after 11yrs and it's now highlighting a possible system restriction. When you bleed the rads is the system water nice and clean?