Is it OK to have a 28mm combined feed and vent pipe connected to near the bottom of the expansion tank without any vent pipe going over the top? Will this present any problems if one wants to flush the system?
Combined feed and vent
- Thread starter patagonia
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Regardless of the size, you will get a mess if you powerflush the system without blocking off, and no effect if it is a normal flush. Personally, I have never been convinced of the use of separate feed and vent pipe, if they are close together, near the pump and do not have horizontal runs, but you are supposed to have them separate.
We used to have them separate, with a pipe going over the top of the expansion tank but I think the feed pipe was only half inch which the chap who installed the new boiler said wasn't enough so he said he was installing a combined feed and vent but we didn't realise he was removing the pipe over the top. The tank has quite a bit of gunge in it.
Isnt it better to have a 28m feed & exp,than a 15mm c/feed and 22m exp.Surely a 28 m c/feed has no chance of blocking and will never need a p/flush to clear that side of the system .so just a blank on the 28mm at the tank,dont have a valve fitted on it and left on.
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I have often converted to a combined feed and vent to fix piping problems within the property.
However for safety reasons the vent should still come out above the cistern. Its best to have a 15 mm feed from the cistern joing the 22/28 vent pipe horizontally at a tee ( to the vertical vent pipe ).
I know they are not in favour but I think they would be a good idea if anyone still fitted a new open vented system.
Tony
However for safety reasons the vent should still come out above the cistern. Its best to have a 15 mm feed from the cistern joing the 22/28 vent pipe horizontally at a tee ( to the vertical vent pipe ).
I know they are not in favour but I think they would be a good idea if anyone still fitted a new open vented system.
Tony
You can easily clean this out. Tie up the ball valve, bail out the water into a bucket, scrub and sponge out the remaining sediment into your bucket. This will prevent it being washed down into the system and contributing to the sediment content.
You can clean out the rest of the system using a chemical cleaner and refill using inhibitor (unless this has already been done), it is a DIY job and may save you the considerable expense of repairs and powerflush if you get a blockage later.
Fit a close fitting lid to keep out dust, detritus, spiders, birds etc and insulate the tank.
Thanks for replies. The system was supposed to have been cleansed and flushed and an inhibitor put in when we had the new boiler installed 5 yrs ago so I don't know why we have this gunge and also kettling in the boiler and ticking in pipes and rads; also one of the rads doesn't seem to get as hot at the bottom as at the top. What cleanser should be used and will the system cleanser do anything about the boiler kettling and ticking in pipes? I could clean out the tank (which has a lid and insulation though it wasn't secured properly till I did it) but I'm afraid this 71 yr old lady isn't up to doing all the draining and flushing herself but I need to know what should be done as I don't think it was done properly last time.
Why are open systems out of favour? I should have thought pressurised systems were a lot more bothersome.
Why are open systems out of favour? I should have thought pressurised systems were a lot more bothersome.
The best, though sentinel is not much less, is called HYPERFLUSH, made by company called Kamco. They will ship it off to you if you do not have a local stockist. They are also very knowledgeable about the actual work and how to overcome problems.
If your tank has noticible amounts of dirt in it, the cleaning was not done properly, no two ways about it.
Yes, open vent systems are becoming obsolete. Some people argue they are better than sealed systems, but that is a bit like saying a Morris Minor is better than a Mercedes because you can start it with the crank handle if the battery is dead, and the merc will need a jumpstart.
The reasons a sealed system is better are various, the main ones being, no soiling up when done properly, no airlocks, better heat transfer, better circulation, immediate visibility when the system develops a leak, radiators possible at any position in the house.
If your tank has noticible amounts of dirt in it, the cleaning was not done properly, no two ways about it.
Yes, open vent systems are becoming obsolete. Some people argue they are better than sealed systems, but that is a bit like saying a Morris Minor is better than a Mercedes because you can start it with the crank handle if the battery is dead, and the merc will need a jumpstart.
The reasons a sealed system is better are various, the main ones being, no soiling up when done properly, no airlocks, better heat transfer, better circulation, immediate visibility when the system develops a leak, radiators possible at any position in the house.
As a DIY job:
You need to find the drain cock which with luck will be by a radiator at the lowest point of the system, preferably next to an external door so you can put a hosepipe on it and run it into a drain. [If you do not have such a drain cock, get someone to fit one (or more). You can get radiator valves which incorporate one http://www.screwfix.com/sfd/i/cat/90/p1050790_l.jpg these are neat and an easy plumbing job to fit.; or it can be fitted to the pipework http://www.screwfix.com/sfd/i/cat/22/p2026322_m.jpg Old drain cocks are sometimes clogged and have to be taken off and poked clean. This causes water spillage which is undesirable in a carpeted room.] If your downstairs radiators are fed from pipes coming down from the ceiling, each such radiator needs a drain.
You turn off the boiler so it cannot fire up or start the pump until you are ready
You clean out the F&E tank and tie up the ball valve so it does not refill yet
You empty the system through your hosepipe (this will get rid of the loose muck) and open the bleed valves on all the rads (starting at the top) so all the water can get out
You close the drain cock and all the bleed screws (it can be useful to have a few spare bleed screws as you might drop one and lose it)
You tip your bottle of chemical cleaner into the F&E tank and untie the ball cock. the fresh water will mix with the chemical and wash it down unto the system
When the F&E stops refilling (i.e. the system is "full" of water) you go round and bleed each radiator (one at a time) until all air has been expelled
Hooray! the system is now full of cleanish water plus cleaning chemical.
You now turn on the boiler and the wall thermostat so the water starts circulating (leave the boiler thermostat set to zero for the moment, so it doesn't get hot while there may still be air bubbles
Leave it to fill and gurgle for a while. When it stops gurgling, bleed all the rads again (air bubbles may have been blown out of the pipes and risen into the rads)
Turn on the boiler and run it as usual at normal temperature for a period (see instructions on the chemical container - some can be safely left for a couple of weeks). Vent the rads daily - there may be bubbles at first but they should settle down. inspect the F&E tank at intervals to see that it is full of water (it might go black - this si OK) and that it is not pumping over from the vent pipe
Drain the system as described earlier; fill it with fresh water to rinse a couple of times. When you feel you have washed out as much dirt as you can, refill. This time, add the Corrosion Inhibitor chemical in the same way.
Run it and vent the rads for a week or so - you should find they stop creating gas and the water looks pretty clean.
This is a simple DIY method - you can see that it involves climbing into the loft several times, but the rest of the work is no more difficult than putting a hose on a tap and venting radiators. It does take a bit of time, though, so if you are paying a professional, he will probably bring a power-flushing machine and do it all in one day, at a cost of some hundreds of pounds.
If you are getting someone in to fit a new drain cock, consider having a Magnaclean fitted as well. This will cost in the region of £100 plus fitting. it is a device that traps black sludge from the water in future to prevent it settling. Although fitting it is a plumbing job, emptying it is a simple householder task and takes only a few minutes. You might do it once a month during the first winter, then once a year.
Sentinel X400 is a desludging chemical cleaner available at your DIY shed or plumbers merchant for about £15 a litre (which will be enough unless you have an abnormally large house). The Corrsosion Inhibitor used on final fill is Sentinel X100 at the same price. Another popular brand is Fernox which is also good. Beware of cheaper brands which may or may not be of equivalent quality. Kamco is a professional brand which you may not find locally.
You need to find the drain cock which with luck will be by a radiator at the lowest point of the system, preferably next to an external door so you can put a hosepipe on it and run it into a drain. [If you do not have such a drain cock, get someone to fit one (or more). You can get radiator valves which incorporate one http://www.screwfix.com/sfd/i/cat/90/p1050790_l.jpg these are neat and an easy plumbing job to fit.; or it can be fitted to the pipework http://www.screwfix.com/sfd/i/cat/22/p2026322_m.jpg Old drain cocks are sometimes clogged and have to be taken off and poked clean. This causes water spillage which is undesirable in a carpeted room.] If your downstairs radiators are fed from pipes coming down from the ceiling, each such radiator needs a drain.
You turn off the boiler so it cannot fire up or start the pump until you are ready
You clean out the F&E tank and tie up the ball valve so it does not refill yet
You empty the system through your hosepipe (this will get rid of the loose muck) and open the bleed valves on all the rads (starting at the top) so all the water can get out
You close the drain cock and all the bleed screws (it can be useful to have a few spare bleed screws as you might drop one and lose it)
You tip your bottle of chemical cleaner into the F&E tank and untie the ball cock. the fresh water will mix with the chemical and wash it down unto the system
When the F&E stops refilling (i.e. the system is "full" of water) you go round and bleed each radiator (one at a time) until all air has been expelled
Hooray! the system is now full of cleanish water plus cleaning chemical.
You now turn on the boiler and the wall thermostat so the water starts circulating (leave the boiler thermostat set to zero for the moment, so it doesn't get hot while there may still be air bubbles
Leave it to fill and gurgle for a while. When it stops gurgling, bleed all the rads again (air bubbles may have been blown out of the pipes and risen into the rads)
Turn on the boiler and run it as usual at normal temperature for a period (see instructions on the chemical container - some can be safely left for a couple of weeks). Vent the rads daily - there may be bubbles at first but they should settle down. inspect the F&E tank at intervals to see that it is full of water (it might go black - this si OK) and that it is not pumping over from the vent pipe
Drain the system as described earlier; fill it with fresh water to rinse a couple of times. When you feel you have washed out as much dirt as you can, refill. This time, add the Corrosion Inhibitor chemical in the same way.
Run it and vent the rads for a week or so - you should find they stop creating gas and the water looks pretty clean.
This is a simple DIY method - you can see that it involves climbing into the loft several times, but the rest of the work is no more difficult than putting a hose on a tap and venting radiators. It does take a bit of time, though, so if you are paying a professional, he will probably bring a power-flushing machine and do it all in one day, at a cost of some hundreds of pounds.
If you are getting someone in to fit a new drain cock, consider having a Magnaclean fitted as well. This will cost in the region of £100 plus fitting. it is a device that traps black sludge from the water in future to prevent it settling. Although fitting it is a plumbing job, emptying it is a simple householder task and takes only a few minutes. You might do it once a month during the first winter, then once a year.
Sentinel X400 is a desludging chemical cleaner available at your DIY shed or plumbers merchant for about £15 a litre (which will be enough unless you have an abnormally large house). The Corrsosion Inhibitor used on final fill is Sentinel X100 at the same price. Another popular brand is Fernox which is also good. Beware of cheaper brands which may or may not be of equivalent quality. Kamco is a professional brand which you may not find locally.
Thanks for replies.
John D:
We have a drain cock fitted to a radiator pipe near a door in the (carpeted) hall. However, this is not the lowest point of the system as the boiler, pump, programmer, motorised valves and a lot of pipework are in the cellar. Would the pump drain the water from that lot through the cock in the hall? We don't have any pipes coming down from the ceiling to any rads; all under the floor.
When you say "see that it isn't pumping over from the vent pipe", since we don't have a pipe going over the top of the expansion tank, do you mean pushing up from the combined feed & vent pipe at the bottom of the tank and raising the level so that it goes out through the overflow pipe over the roof?
The gunge in the tank is orange/rusty coloured by the way rather than black.
I might screw up my courage to have a go and doing it myself but first I need to get the motorised valve fixed. The plumber who broke the tongues off the head on Monday seems to have disappeared (his office say he phoned in to say he had a family emergency and won't be in today and they have no idea whether he has done anything about getting a replacement or not. See thread under "Motorised valve stuck". In the meantime, we now have no heating downstairs unless I press the valve down onto the pipe and then the boiler fires, but it jumps up with a bang if I take my hand off. I wonder if I would be able to tape it down. Very worrying as we have a small baby visiting at the weekend.
John D:
We have a drain cock fitted to a radiator pipe near a door in the (carpeted) hall. However, this is not the lowest point of the system as the boiler, pump, programmer, motorised valves and a lot of pipework are in the cellar. Would the pump drain the water from that lot through the cock in the hall? We don't have any pipes coming down from the ceiling to any rads; all under the floor.
When you say "see that it isn't pumping over from the vent pipe", since we don't have a pipe going over the top of the expansion tank, do you mean pushing up from the combined feed & vent pipe at the bottom of the tank and raising the level so that it goes out through the overflow pipe over the roof?
The gunge in the tank is orange/rusty coloured by the way rather than black.
I might screw up my courage to have a go and doing it myself but first I need to get the motorised valve fixed. The plumber who broke the tongues off the head on Monday seems to have disappeared (his office say he phoned in to say he had a family emergency and won't be in today and they have no idea whether he has done anything about getting a replacement or not. See thread under "Motorised valve stuck". In the meantime, we now have no heating downstairs unless I press the valve down onto the pipe and then the boiler fires, but it jumps up with a bang if I take my hand off. I wonder if I would be able to tape it down. Very worrying as we have a small baby visiting at the weekend.
you need a drain at the lowest point. The pump cannot raise it from the cellar (it would probably run dry and wear out)
There might be a drain already on the boiler somewhere, if not it is possible to undo a joint, but I think this would be a bad move for you, as you might have trouble getting it together again. If you get a plumber who charges by the hour I would have thought he could easily find, or fit, a valve for you. If you are having a new one fitted, a full-bore valve lets the water gush out much faster than the ones in my pic, and the faster flow is better for washing out dirt. in the cellar it does not need to be so small and neat.
If you do not drain from the lowest point you would have to drain, fill, circulate, drain to try to dilute the remaining sediment (although a Magnaclean will trap circulating black sediment it will not filter out any other rubbish).
The rusty-coloured sediment in the F&E is quite usual, I have heard different explanations of why it is black in the rads and red in the tank
The black stuff will stick to a magnet quite easily, but the red hardly at all.
There might be a drain already on the boiler somewhere, if not it is possible to undo a joint, but I think this would be a bad move for you, as you might have trouble getting it together again. If you get a plumber who charges by the hour I would have thought he could easily find, or fit, a valve for you. If you are having a new one fitted, a full-bore valve lets the water gush out much faster than the ones in my pic, and the faster flow is better for washing out dirt. in the cellar it does not need to be so small and neat.
If you do not drain from the lowest point you would have to drain, fill, circulate, drain to try to dilute the remaining sediment (although a Magnaclean will trap circulating black sediment it will not filter out any other rubbish).
The rusty-coloured sediment in the F&E is quite usual, I have heard different explanations of why it is black in the rads and red in the tank
The black stuff will stick to a magnet quite easily, but the red hardly at all.DIYnot Local
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