I recently fitted a shower pump to my gravity fed dometic hot water system using a Surrey Flange to connect the pump to the HW cyclinder head, and a new dedicated 22mm cold feed. The shower feed is tee'd off the side of the flange and the DHWS from the top per the instructions. The cold water feed to the Hot water cylinder is 28mm , and so is the hot water outlet from the cylinder. The shower is fine but after a week or so the HW pressure in the house goes down and I have to bleed an airlock which seems to be forming in the original hot water supply pipe to the rest of the house. I imagine air might be getting drawn down the hot water supply vent, but I have no idea how to stop this happening ? Is this whats happening and any ideas on how to fix it ?
Shower Pump Airlock
- Thread starter peterbu
- Start date
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I close the cold feed to the cylinder and force high pressure cold water from the kitchen tap up the hot water supply until it overflows from the DHWS vent and that clears it. I think the air is collecting around where the DHWS vent tee's off- I can hear a trickling noise from around there before bleeding it - about a foot or so from the the Surrey flange at the top of the cylinder
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L
longdogs
Can't see too well from the pic but does the DHW pipe incline slightly up towards the tee/vent as it should?
Thanks guys for these ideas . The DHW connection is horizontal so I could try to incline it but at 28mm and a foot of clearance might be a challenge - how many degrees are you talking about ? Also the airvent idea - would that be on the inputs or outputs from the pump ? The air build up I think is on the input side at the moment
cheers
Peter
cheers
Peter
Peter,
Your post is somewhat spooky! I have the exact same problem and tried everything. My configuration is also identical to yours. I can also easily clear the airlock to the rest of the house in the same way you describe by blasting the cold mains water back up from the kitchen but the airlock between the hot water tank and the pump is a nightmare to clear as the mains water from the kitchen simply blows into the tank through the surrey flange and not through the pump. I really am at my wits end with this one as it just does not make sense. Did you have any sucess with the air vents on top of the pump? This would not be an easy one for me to do as my bl**dy tiler went and tiled over the pump!! I am more interested in working out where the air is coming from and then fix that part. I thought the point of the surrey flange was to prevent this? I'm getting to the point now where i am tempted to cut a hole in the side of the tank and fit one of those types of flanges (is it Essex?) but again would rather KNOW this would fix the problem. Any further thoughts from anyone??
Peter R.
Your post is somewhat spooky! I have the exact same problem and tried everything. My configuration is also identical to yours. I can also easily clear the airlock to the rest of the house in the same way you describe by blasting the cold mains water back up from the kitchen but the airlock between the hot water tank and the pump is a nightmare to clear as the mains water from the kitchen simply blows into the tank through the surrey flange and not through the pump. I really am at my wits end with this one as it just does not make sense. Did you have any sucess with the air vents on top of the pump? This would not be an easy one for me to do as my bl**dy tiler went and tiled over the pump!! I am more interested in working out where the air is coming from and then fix that part. I thought the point of the surrey flange was to prevent this? I'm getting to the point now where i am tempted to cut a hole in the side of the tank and fit one of those types of flanges (is it Essex?) but again would rather KNOW this would fix the problem. Any further thoughts from anyone??
Peter R.
Looks like the turbulance created by the shower pump is causing air to be drawn in and it is setteling in the horizontal section.
Would it be possible to connect a second vent where the solder elbow is on the top of the cylider. Route this new vent into the original with a T a little higher up ? This would vent the horizontal section at both ends !!
Would it be possible to connect a second vent where the solder elbow is on the top of the cylider. Route this new vent into the original with a T a little higher up ? This would vent the horizontal section at both ends !!
Guys
Thanks for the input and glad I'm not the only one with this problem !
The air vent option sounds like easiest but I'm concerned about the idea of having air vents immediately beside the pump inlets in case that just allows more air to be drawn in to the system ? I guess these things act like a one way valve and only let air out when the pump stops running so it may do the trick, but would just like to confirm that was where you mean't them to be positioned ???
Also with a bit more work I could go for one of the other options with the vent pipe from the top. Putting in an extra vent from the cylinder solder bend to a tee further up would be easy enough I think. But it was also mentioned that the horizontal pipe should also have a small incline to it which at the moment it doesn't. If I'm going to work on that end of the system I'd prefer to put in the incline as well, but with 28mm copper over a couple of feet I don't think I can bend it and still get it connected to 90 degree bends at either end ? Would using 28mm Hep instead of copper do it - if you get such a thing - or is there a better way to get say a 50mm incline over this short section ?
cheers
Peter
Thanks for the input and glad I'm not the only one with this problem !
The air vent option sounds like easiest but I'm concerned about the idea of having air vents immediately beside the pump inlets in case that just allows more air to be drawn in to the system ? I guess these things act like a one way valve and only let air out when the pump stops running so it may do the trick, but would just like to confirm that was where you mean't them to be positioned ???
Also with a bit more work I could go for one of the other options with the vent pipe from the top. Putting in an extra vent from the cylinder solder bend to a tee further up would be easy enough I think. But it was also mentioned that the horizontal pipe should also have a small incline to it which at the moment it doesn't. If I'm going to work on that end of the system I'd prefer to put in the incline as well, but with 28mm copper over a couple of feet I don't think I can bend it and still get it connected to 90 degree bends at either end ? Would using 28mm Hep instead of copper do it - if you get such a thing - or is there a better way to get say a 50mm incline over this short section ?
cheers
Peter
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