The height is around 2 -3 metres, the air vent slopes up an over and bends in the f/e tank.
Air being vented into Open Vented CH system, advice
- Thread starter rrwfotr
- Start date
The height is around 2 -3 metres, the air vent slopes up an over and bends in the f/e tank.
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maybe replacing the air sep for nwer one, of using the H wud work. i usually take the one u have out
is the air seperator I have, not very good?
The cold feed position is the "neutral point" where the pump is neither pushing or pulling. Everything from the feed position (if it is on the HW return, then the boiler) to the pump is under negative pressure (suction) and everything after the pump back round to the feed position (boiler) is under positive pressure (being pushed). As the expansion pipe is between the boiler (neutral point) and the pump this part of the system is negative pressure.
You have replaced the previous pump with a higher head pump so at speed 2 the pump head is greater than the height between the pump and the FE tank which causes the air to be drawn in.
The only way to cure this is to alter the feed to tee in just after and within 150mm of the expansion preferrably with an inverse connection.(looping down and back up).
I hope you followed this because i can't be bothered drawing it
You have replaced the previous pump with a higher head pump so at speed 2 the pump head is greater than the height between the pump and the FE tank which causes the air to be drawn in.
The only way to cure this is to alter the feed to tee in just after and within 150mm of the expansion preferrably with an inverse connection.(looping down and back up).
I hope you followed this because i can't be bothered drawing it
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I'm confused the air does not appear to be coming from the air vent in the loft. I've had it tested and no air is coming down. There appear to no leaks anywhere. Just can't figure where the air may be coming from. Any ideas chaps?
The pump head has nothing to do with the height between FE tank and pump.
Grundfos say that the minimum distance between pump and water level in the FE tanks is 1.4 metres.
To the OP
How far above the FE tank water level is the top of the bend in the vent pipe?
Fill a container with water, dip the end of the vent pipe in the water and check if the water is sucked into the vent pipe. If it does, the air is getting into the system there.
On your first picture you have the pipe on the left going down labelled "main flow from F/E tank". Don't you mean the top left pipe? The bottom left one will be the flow connection from the boiler.
The arrow on the pump should be pointing down.
I think your problem is almost definately sludge, I can't see your system needing a 15/60 pump - 22mm pipework says it's not a terribly big system, unless the pipes are undersized, not giving you flow for all your rads.
IF it was lying horizontal with the branches upwards - It looks like it would form the correct way to position vent/cold feed
(I know about the dip in CF previously mentioned , but it`s not strictly necessary) I think it`s yet another wrongly installed airsep. Radiators which are cold at the bottom normally means the rads have sludge in them.
Are the two rads in question at the end of the chain, i.e furthest from the pump? If so, it could be a matter of getting the balance right.
You haven't answered my earlier questions
My thought also. We also have the fact that the pump is pumping down, which can cause problems. Grundfos say:Nige F said:
It is preferable to install Grundfos circulators in a vertical pipe pumping upwards. This position ensures that the pump shaft is horizontal, which reduces the thrust bearing load and ensures positive air purging from both the rotor chamber and impeller housing.
Pumping downwards in a vertical pipe is not recommended as this may lead to air locking of the pump, with resultant loss of performance. However, pumping downwards is acceptable provided an effective air vent is incorporated in the system, before the pump.
I checked the air vent with the water cup method and it appears no air is being sucked in.
The rads that only heat half way are the furthest away from the pump and the largest
I have flushed the system and tried to balance the system with x400 however this did not resolve the issue.
I have noticed that the boiler themostat ) potterton proile 80e gas is set to 3 should I increase the boiler themosat so water is heated to higher temp at the moment the rads get hot but not really hot. I'm think maybe the water is getting colder on the last leg on the flow. I'm worried about increasing the boiler themostat just incase I whack it up to maxium output, what are the pros and cons of this i.e imcreasing the themostat may this bei the reason I'm not gettintg output on last two rads? .
The rads that only heat half way are the furthest away from the pump and the largest
I have flushed the system and tried to balance the system with x400 however this did not resolve the issue.
I have noticed that the boiler themostat ) potterton proile 80e gas is set to 3 should I increase the boiler themosat so water is heated to higher temp at the moment the rads get hot but not really hot. I'm think maybe the water is getting colder on the last leg on the flow. I'm worried about increasing the boiler themostat just incase I whack it up to maxium output, what are the pros and cons of this i.e imcreasing the themostat may this bei the reason I'm not gettintg output on last two rads? .
That's good
Thought that might be the case
I didn't know that X400 was used to balance a system; I always thought it was a system cleaner. You learn something new every day on this forum.
Do you have a wall thermostat in the hall or living room? If you do, set the boiler thermostat to max setting. The wall thermostat will control when it goes on and off.
Very likely.
PS
X 400 needs to be left in the system for about four weeks for it to do any good. Longer is OK.
How to Balance a CH System
Sorry typo I did leave x400 in for a month.and the flushed out system.
So putting up the bolier themostat may resolve the issue with the collder last two rads which only heat half way?
If I set the boiler to maxium output are there any issues / problems I may have? I have a room themostat which I can use/set.
So putting up the bolier themostat may resolve the issue with the collder last two rads which only heat half way?
If I set the boiler to maxium output are there any issues / problems I may have? I have a room themostat which I can use/set.
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