J
JimHearne
Hi all,
Sorry, this is a bit of a saga but I'm going to try and give all the details at the start.
How it was:
2 Storey house. Boiler on ground floor, indirect vented hot water cylinder on first floor, cold water tank sitting on the rafters in the loft.
One bathroom with just a bath (no shower), One en-suite with a thermostatic mixer shower (both hot and cold gravity feed), one downstairs loo with sink.
All hot water pipes run under the floors, nothing goes up and through the loft except the separate gravity cold water feed for the en-suite shower which goes from the cold water tank directly down to the shower.
Mains water pressure 6.5bar.
Somewhere under the floor between the hot water cylinder and the bathroom the pipe goes from 22mm to 15mm.
Hot water cylinder is about 3m from the bathroom and I'm pretty sure the pipes carry on from there to the en-suite under the floor still.
No problems apart from the thermostatic en-suite shower being quite fussy about doing warm, it tends to either do hot or cold and whistle at the switchover, I put this down to the low gravity water pressure.
Anyway, we decided to replace the standard bath in the main bathroom with a shower bath with the shower feed from mixer taps.
After this was all done we realised that that the cold water in this bathroom was mains pressure and the hot water was only gravity, so the slightest opening of the cold water tap just stopped the hot water (and probably forced cold water back into the hot).
Did a lot of reading on the net, and realised that without ripping out the newly fitted bath and tiles to take up the laminate floor and floor boards, and run in new pipes, that the only option was to fit a pump on the hot water to try and match the pressure of the cold water.
I know there will be some here that will say that's not a good idea, or it won't work, but I did consult with a pump supplier first, and it does seem to work, it's not the actual problem I'm having.
Anyway, got a pump ( Stuart Turner Showermate U2.6Bar Single 46534) and fitted it to the feed to the bath hot water tap, actually under the end of the bath.
Fitted a pressure regulator to the mains cold water feed to the bath cold tap to drop that down to about 2.6 bar as well.
I'd read about the problems of sucking air in from the vent with the pump so I fitted a Surrey flange to the top of the hot water tank.
The original setup just had the hot water outlet coming out of the top of the tank, 90 degree bend to horizontal, across to the side of the tank, then a T with the vent pipe going straight up to the loft and the hot water outlet going straight down under the floor.
My first attempt with the Surrey flange had the side outlet from the Surrey flange going horizontally across and then 90 degrees down into the original outlet pipe.
The top outlet from the Surrey flange went straight into a 90 degree bend, across horizontally (maybe a little down hill after all soldered up) and then another 90 degree bend to go up onto the original vent pipe.
I know this isn't quite normal as usually you would only have the feed for a shower pump from the Surrey flange but I couldn't find or think of any reason why it would cause problems having all the hot water going through it.
The pump seems to run quite happily but we've not been using it at all yet as the shower screen etc still needs fitting.
So, this was all done (not using the pumped shower at all) but after a couple of days the hot water pressure at the en-suite shower dropped right away, so that in the end it barely trickled out.
The water pressure at the other hot taps seemed to have dropped as well, even those downstairs.
After some messing about with taps and then switching on the pump for a min or so it seemed to suck some air through (I know this is very bad for them), and all the pressures were back to normal at the other shower and taps.
But the problem re-occurred every couple of days, needing the pump (which we weren't using otherwise) to be turned on to seemingly suck air out of the system to fix it.
I thought maybe the problem was air being trapped in the 2 horizontal pipes I had above the cylinder (the outlet and vent) so I removed them all and replaced the vent pipe with a section going up at 45 degrees to the vertical pipe.
And the hot water outlet pipe I replaced with a curved pipe I bent to a bit bigger radius than the cylinder so there was minimal horizontal section.
But, the airlock problems remain.
The Surrey flange I have seems to have a small rubber vent with a small hole in it between the outlet and the vent sections, I assume so any small amount of air that does get stuck in the outlet pip can still escape into the vent pipe.
When the hot water looses pressure water can be heard running in the outlet pipe from the cylinder, when there is normal pressure you can't hear this.
The vent pipe is hot and gradually gets cooler the higher you go (but still hot up to the ceiling), the end of the pipe above the cold water tank is above the water surface.
I can't figure out where the air is getting into the system, fitting the Surrey flange seems to have created a problem we didn't have before.
I can take some pictures of the pipework around the cylinder tomorrow.
If you have read this far, any thoughts please ?
Many thanks,
Jim
Sorry, this is a bit of a saga but I'm going to try and give all the details at the start.
How it was:
2 Storey house. Boiler on ground floor, indirect vented hot water cylinder on first floor, cold water tank sitting on the rafters in the loft.
One bathroom with just a bath (no shower), One en-suite with a thermostatic mixer shower (both hot and cold gravity feed), one downstairs loo with sink.
All hot water pipes run under the floors, nothing goes up and through the loft except the separate gravity cold water feed for the en-suite shower which goes from the cold water tank directly down to the shower.
Mains water pressure 6.5bar.
Somewhere under the floor between the hot water cylinder and the bathroom the pipe goes from 22mm to 15mm.
Hot water cylinder is about 3m from the bathroom and I'm pretty sure the pipes carry on from there to the en-suite under the floor still.
No problems apart from the thermostatic en-suite shower being quite fussy about doing warm, it tends to either do hot or cold and whistle at the switchover, I put this down to the low gravity water pressure.
Anyway, we decided to replace the standard bath in the main bathroom with a shower bath with the shower feed from mixer taps.
After this was all done we realised that that the cold water in this bathroom was mains pressure and the hot water was only gravity, so the slightest opening of the cold water tap just stopped the hot water (and probably forced cold water back into the hot).
Did a lot of reading on the net, and realised that without ripping out the newly fitted bath and tiles to take up the laminate floor and floor boards, and run in new pipes, that the only option was to fit a pump on the hot water to try and match the pressure of the cold water.
I know there will be some here that will say that's not a good idea, or it won't work, but I did consult with a pump supplier first, and it does seem to work, it's not the actual problem I'm having.
Anyway, got a pump ( Stuart Turner Showermate U2.6Bar Single 46534) and fitted it to the feed to the bath hot water tap, actually under the end of the bath.
Fitted a pressure regulator to the mains cold water feed to the bath cold tap to drop that down to about 2.6 bar as well.
I'd read about the problems of sucking air in from the vent with the pump so I fitted a Surrey flange to the top of the hot water tank.
The original setup just had the hot water outlet coming out of the top of the tank, 90 degree bend to horizontal, across to the side of the tank, then a T with the vent pipe going straight up to the loft and the hot water outlet going straight down under the floor.
My first attempt with the Surrey flange had the side outlet from the Surrey flange going horizontally across and then 90 degrees down into the original outlet pipe.
The top outlet from the Surrey flange went straight into a 90 degree bend, across horizontally (maybe a little down hill after all soldered up) and then another 90 degree bend to go up onto the original vent pipe.
I know this isn't quite normal as usually you would only have the feed for a shower pump from the Surrey flange but I couldn't find or think of any reason why it would cause problems having all the hot water going through it.
The pump seems to run quite happily but we've not been using it at all yet as the shower screen etc still needs fitting.
So, this was all done (not using the pumped shower at all) but after a couple of days the hot water pressure at the en-suite shower dropped right away, so that in the end it barely trickled out.
The water pressure at the other hot taps seemed to have dropped as well, even those downstairs.
After some messing about with taps and then switching on the pump for a min or so it seemed to suck some air through (I know this is very bad for them), and all the pressures were back to normal at the other shower and taps.
But the problem re-occurred every couple of days, needing the pump (which we weren't using otherwise) to be turned on to seemingly suck air out of the system to fix it.
I thought maybe the problem was air being trapped in the 2 horizontal pipes I had above the cylinder (the outlet and vent) so I removed them all and replaced the vent pipe with a section going up at 45 degrees to the vertical pipe.
And the hot water outlet pipe I replaced with a curved pipe I bent to a bit bigger radius than the cylinder so there was minimal horizontal section.
But, the airlock problems remain.
The Surrey flange I have seems to have a small rubber vent with a small hole in it between the outlet and the vent sections, I assume so any small amount of air that does get stuck in the outlet pip can still escape into the vent pipe.
When the hot water looses pressure water can be heard running in the outlet pipe from the cylinder, when there is normal pressure you can't hear this.
The vent pipe is hot and gradually gets cooler the higher you go (but still hot up to the ceiling), the end of the pipe above the cold water tank is above the water surface.
I can't figure out where the air is getting into the system, fitting the Surrey flange seems to have created a problem we didn't have before.
I can take some pictures of the pipework around the cylinder tomorrow.
If you have read this far, any thoughts please ?
Many thanks,
Jim
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