Hot water running from CH header tank overflow

[nocturnal]

Hot water is trickling from the header tank overflow pipe only when the CH is running. It is a dual system (CH or hot water with motorised valves) and no drip occurs when only heating the hot water. No drips either when boiler is off so the ball valve is OK.

Now my small 2 up 2 down house only has 4 rads in it at the moment and has been like that for years (I'll be doing a big refurb on it soon). The rad in the living room is full of sludge, 2/3 of it is a massive cold spot. I bought X400 for the system (dreaded 10mm microbore throughout the house) but I want to put a drain valve in a rad for future convenience and upsize a few of the rads so I haven't used it yet. Would X400 clear out a huge amount of sludge in a rad or better to replace it? It is under-rated anyway for the room (housing association built the house and it is terrible).

Would a X400 chemical flush cure the hot water running out the overflow? I don't want it running out the overflow and not having a chance to work.

No fun staying in the house at the minute, I'm not using the CH and sleeping in the living room with an electric fire going.

 

[SimonG]

X400 will only work if you can get it to circulate. Could have partial blockage somewhere causing the pumping over.

 

[Riley]

I would say that in need of a proper professional power flush

 

[Harvest Fields]

I would check out the condition and effectiveness of your pump to begin with.

 

[nocturnal]

Thanks, the circulation seems OK, all the rads and hot water cylinder heat up quickly. The rads without sludge are as good as can be albeit they are too small.

Power flushing is out of the question, there is circulation so I'll drain it down, add the X400 and leave the header tank filled just above the outlet pipe level and hope none spits out. I'll be very surprised if the X400 shifts that amount of blockage in the living room rad but I've never used it before. I'll get a new rad for it if so, I need a Myson bleed screw and brackets from it anyway for another rad I took off years ago for a kitchen refurb that didn't happen.

The house is 19 years old but when the housing association owned it they didn't look after it, never replaced the inhibitor etc. Same inhibitor if there indeed ever was any in the system since the house was built... Pure cowboys, all the neighbours had the same problems. Hence the reason for the sludge, partial blockage etc. Cheers

 

[nocturnal]

I'll have a look and feel of the pump too, it sounded OK last night though.

Brrrr dreading the thought of starting this when getting home at 2am, it was 4°C inside last night.

 

[Riley]

Thanks, the circulation seems OK, all the rads and hot water cylinder heat up quickly. The rads without sludge are as good as can be albeit they are too small.

Power flushing is out of the question, there is circulation so I'll drain it down, add the X400 and leave the header tank filled just above the outlet pipe level and hope none spits out. I'll be very surprised if the X400 shifts that amount of blockage in the living room rad but I've never used it before. I'll get a new rad for it if so, I need a Myson bleed screw and brackets from it anyway for another rad I took off years ago for a kitchen refurb that didn't happen.

The house is 19 years old but when the housing association owned it they didn't look after it, never replaced the inhibitor etc. Same inhibitor if there indeed ever was any in the system since the house was built... Pure cowboys, all the neighbours had the same problems. Hence the reason for the sludge, partial blockage etc. Cheers

Why is powerflushing out of the question??

 

[Burger]

Hot water is trickling from the header tank overflow pipe only when the CH is running. It is a dual system (CH or hot water with motorised valves) and no drip occurs when only heating the hot water. No drips either when boiler is off so the ball valve is OK.

Now my small 2 up 2 down house only has 4 rads in it at the moment and has been like that for years (I'll be doing a big refurb on it soon). The rad in the living room is full of sludge, 2/3 of it is a massive cold spot. I bought X400 for the system (dreaded 10mm microbore throughout the house) but I want to put a drain valve in a rad for future convenience and upsize a few of the rads so I haven't used it yet. Would X400 clear out a huge amount of sludge in a rad or better to replace it? It is under-rated anyway for the room (housing association built the house and it is terrible).

Would a X400 chemical flush cure the hot water running out the overflow? I don't want it running out the overflow and not having a chance to work.

No fun staying in the house at the minute, I'm not using the CH and sleeping in the living room with an electric fire going.

Can you turn the pump speed setting down for the time being until you have rectified your issue?

 

[nocturnal]

Hi, sorry for delay, I only managed to get at it today.

Problem is only a bust float valve, bought a Pegler for it but never got fitting it as tools on a job. Temporary fix, just switched off header tank supply and cupped 1/2 water out of header tank. CH on again!

Trying to get at this installation is a nightmare, about 2 foot high with 300mm insulation, header tank tight under trusses, expansion pipe nailed to trusses. I couldn't even take off the header tank cover, inlet valve is on hidden side...

The joys of building

Cheers

 

[Chuck]

Trying to get at this installation is a nightmare, about 2 foot high with 300mm insulation, header tank tight under trusses, expansion pipe nailed to trusses. I couldn't even take off the header tank cover, inlet valve is on hidden side...

Can you replace the expansion tank with a 'coffin tank' (i.e. low narrow and long) to gain a better access? Otherwise you may have to get a roofer involved to gain access from the outside, which will add £500 to a job that should cost pennies and will still need to be redone every five years or so.

I recommend you bite the bullet and fix it properly and permanently by converting the CH system to a sealed-pressurised one.