Been having a lot of problems with my Central heating recently. Started when I replaced a bathroom radiator and when I refilled the system some of the radiators would not get hot. Called a plumber who diagnosed a powerflush was required. £450 later I still had three cold radiators. After a row with the plumber who said it was my fault because I must have disturbed some muck when I drained down first time, I eventually got all the rads working by removing them, hosing them through and then turning them on one by one. Only problem is now the system is overpumping even when the pump is on it's lowest setting. The vent pipe is at least 4ft above the header tank before it comes back down. The pump has been replaced and the pipework layout is (coming from the pump upwards) first the cold water feed which is about 4 inches from the pump and then the vent pipe another couple of inches further on. The plumber (just about on speaking terms) says it's probably a partially blocked manifold and he will charge £50 an hour to find it and then clean it out/replace it. Does this sound sensible or should I be looking at something else? The heating and hot water are working ok but I am worried that if it's not sorted The system will be corroding from the inside.
Overpumping 8mm Microbore system
- Thread starter steviec12
- Start date
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WHat you're describing is this:
That CAN't pump over (water out of the vent) unless the pump's in backwards because the pressure will always be higher at the feed than the vent.
I suspect there's a blockage between the feed and the vent - it'll be at the base of the feed pipe.
What's covered by a powerflush isn't "standard". There should be a contract ( ! ) which states whether further work is chargeable or not.
A plumber would argue that he's done the flushing operation, it is't his fault there are unflushable blockages, and the customer would argue that he (plumber)hasn't flushed it, and he (customer) doesn't know or care how hard the deposits might be.
If I had to arbitrate - for £450, how many rads? 7 or 8, plumber clears it free, 12 or more - you contribute. 10, argue!
That CAN't pump over (water out of the vent) unless the pump's in backwards because the pressure will always be higher at the feed than the vent.
I suspect there's a blockage between the feed and the vent - it'll be at the base of the feed pipe.
What's covered by a powerflush isn't "standard". There should be a contract ( ! ) which states whether further work is chargeable or not.
A plumber would argue that he's done the flushing operation, it is't his fault there are unflushable blockages, and the customer would argue that he (plumber)hasn't flushed it, and he (customer) doesn't know or care how hard the deposits might be.
If I had to arbitrate - for £450, how many rads? 7 or 8, plumber clears it free, 12 or more - you contribute. 10, argue!
Pump over is caused by incorrect plumbing. Nothing at all to do with 8mm microbore pipe.
The feed/ expansion and vent pipes are not located correctly in relation to the pump. Fix these and all will be sorted.
WRT to three cold rads, is the system balanced?
The feed/ expansion and vent pipes are not located correctly in relation to the pump. Fix these and all will be sorted.
WRT to three cold rads, is the system balanced?
I agree with ChrisR, but I would suggest that yu ask your 'plumber' to fit a myson aerjec or similar instead of the feed/ vent arrangement you have already and move the pump to about 300mm from the outlet of aerjec. Get him to change cold feed to 22mm as well. Although in theory what you have should work I have found that the above suggestions seems to 'cure' problems like yours.
£50 /hr, I think thats a bit over the top or does that include VAT?
£50 /hr, I think thats a bit over the top or does that include VAT?
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If the pipework layout is as shown in ChrisR's sketch then, as DP says, this in incorrect. The open vent pipe should have a clear path from the boiler to the feed tank which in that layout it does not having to pass through the pump first.
The correct arrangement from the boiler should be open vent, cold feed connection (no more than 150mm from open vent connection) then pump.
As has been said, an air seperator could be installed at the junction of flow pipe/open vent. Whilst these are good for expelling air from a system on first fill they can cause problems as if there is an air leak elsewhere on the system you would never actually know about it.
Not in some parts of Hampshire it's not or indeed in Surrey.
The correct arrangement from the boiler should be open vent, cold feed connection (no more than 150mm from open vent connection) then pump.
As has been said, an air seperator could be installed at the junction of flow pipe/open vent. Whilst these are good for expelling air from a system on first fill they can cause problems as if there is an air leak elsewhere on the system you would never actually know about it.
Not in some parts of Hampshire it's not or indeed in Surrey.
Chris can certainly draw good diagrams.
In the diagram plumping right of pump will be at high pressure, left of pump at low pressure. Both feed and vent pipes will be very nearly at same pressure (high). Move the pump to right of aforementioned connections, pressure on F+V will now be low pressure.
Now fit the pump BETWEEN the feed and vent, feed will be at low pressure and vent at high. Water will be drawn from the cistern to raise the level in the vent. Pump over will take place. 8mm pipe is not even in the picture. You can connect the rads with 4” pipe, pump over will not be eliminated.
£50 per hour is excessive if you cannot effect cures on systems on its knees. Just right if you are following others who cannot cure the problems. There are outfits out there who are charging a lot more for a lot less and getting away with it. To charge 50 to runs pipes is not on, but charge less to diagnose defects and bring to life for less is not on either.
In the diagram plumping right of pump will be at high pressure, left of pump at low pressure. Both feed and vent pipes will be very nearly at same pressure (high). Move the pump to right of aforementioned connections, pressure on F+V will now be low pressure.
Now fit the pump BETWEEN the feed and vent, feed will be at low pressure and vent at high. Water will be drawn from the cistern to raise the level in the vent. Pump over will take place. 8mm pipe is not even in the picture. You can connect the rads with 4” pipe, pump over will not be eliminated.
£50 per hour is excessive if you cannot effect cures on systems on its knees. Just right if you are following others who cannot cure the problems. There are outfits out there who are charging a lot more for a lot less and getting away with it. To charge 50 to runs pipes is not on, but charge less to diagnose defects and bring to life for less is not on either.
N
namsag
The guy has said from the pump up then cold feed and open vent... he has not said pump is pumping up towards them , if the pump is pumping away from them the configuration as we all know is correct. Power flushing microbore is not always affective it is always better to take rads off and flush with a hose and then cut out out the manifolds and clear all muck out off these.
Steviec12 there is an arrow on the pump housing is it pointing to the open vent/cold feed or is it pointing away from them
Steviec12 there is an arrow on the pump housing is it pointing to the open vent/cold feed or is it pointing away from them
N
namsag
DP yeah i know he says pumping over , have seen loads of correctly configured systems even with air seperators pump over caused by blockages in the system
Thanks for the replies all. Good diagram by Chris but the pump is fitted the correct way round (The arrow is pointed away from the feed pipe). The system is overpumping through the vent pipe into the F&E tank. I am getting the plumber back in and as it's 12 rads will "negotiate" as suggested. I think checking the feed pipe where it tee's in near the pump will be a good first check. If not I suppose it's find the manifold and clean out unless anyone has any other suggestions? Having paid £450 for a Powerflush and then spent a weekend taking off and cleaning out all the rads and then balancing the system I'm feeling a bit hacked off that I still have a problem.
N.B £50 an hour seems pretty standard round this part of Surrey/Hants.
N.B £50 an hour seems pretty standard round this part of Surrey/Hants.
When the vent is pumping over, if you plugged up (momentarily ONLY) the feed outlet at the cistern, does the vent pump no more?
If answer is yes, then check plumbing as pump may well be between feed and vent pipe
If answer is yes, then check plumbing as pump may well be between feed and vent pipe
Finally got this sorted. Got the plumber to check out the feed pipe where it tee'ed in next to the vent pipe. It was solid with black sludge that had set like concrete. Once the pipework was replaced no more pumping over and the central heating works better than ever.
Thanks for all the help guys!
Thanks for all the help guys!
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