Hi All, can someone help me I am replacing our bathroom suite including bath shower mixer taps,mains feed for the cold water but tank feed for the hot and looking for a mixer tap on the internet is a nightmare, in very plain english how do I calculate the pressure as some will only work on 0.5 bar or more some but very few on less and I am told that as I live in a bungalow the pressure will not be very high,THANKS
plumbing
- Thread starter reg7
- Start date
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Most straightforward way to measure pressure generated by gravity (your present hot-water system) is, every metre above the draw-of point (shower head on the riser rail - most likely) generates 0.1bar. i.e 10m difference in height = 1.0 bar.
So, likely maximum pressure (static - when water is still) would be 0.2-0.3 bar in a bungalow.
AND, DO NOT mix mains pressure coldwater and tankfed hot-water in a bath/shower mixer. the cold water will push any hot flow back towards the storage vessel. Even (double)check/one-way valves (as required by water regs) would be problematic as it would further restrict hot flow through them to the bath/shower mixer.
So, I would suggest either, a) (cheapest) tank fed cold water - at same pressure as hot, & a shower pump to boost filling/flowrates - you may need to enlarge both capacities of hot-water storage vessel/domestic storage cistern in roofspace to minimise water starvation.
b) dearer, a mains pressure unvented cylinder with balanced hot&cold pressures
c) possibly dearer yet, a 'combination' boiler oil/gas to provide effectivley mains pressure instantanious hot water provision.
d) (not very likely) bury the bath so deep in the floor you get 0.5bar pressure.
DH
BTW, if you are in an NR postcode I am happy to provide a competitive quote for a) to c)
So, likely maximum pressure (static - when water is still) would be 0.2-0.3 bar in a bungalow.
AND, DO NOT mix mains pressure coldwater and tankfed hot-water in a bath/shower mixer. the cold water will push any hot flow back towards the storage vessel. Even (double)check/one-way valves (as required by water regs) would be problematic as it would further restrict hot flow through them to the bath/shower mixer.
So, I would suggest either, a) (cheapest) tank fed cold water - at same pressure as hot, & a shower pump to boost filling/flowrates - you may need to enlarge both capacities of hot-water storage vessel/domestic storage cistern in roofspace to minimise water starvation.
b) dearer, a mains pressure unvented cylinder with balanced hot&cold pressures
c) possibly dearer yet, a 'combination' boiler oil/gas to provide effectivley mains pressure instantanious hot water provision.
d) (not very likely) bury the bath so deep in the floor you get 0.5bar pressure.
DH
BTW, if you are in an NR postcode I am happy to provide a competitive quote for a) to c)
Tony, I am glad someone else is awake on here....
Of course an Essex address will not be an NR Postcode, but the offer stands, I can travel..... - just may not be such a competetive quote anymore though!
DH
I do note that you have yet to comment on the 'real issues' here.
Another alternative is a 'pressure reducing valve' but I am not aware of one that goes down, to say, 0.2bar, and the issues regarding backflow prevention stand of course
Of course an Essex address will not be an NR Postcode, but the offer stands, I can travel..... - just may not be such a competetive quote anymore though!
DH
I do note that you have yet to comment on the 'real issues' here.
Another alternative is a 'pressure reducing valve' but I am not aware of one that goes down, to say, 0.2bar, and the issues regarding backflow prevention stand of course
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I only post if I think that I can add something constructive to the answers.
You have pointed out the pitfalls of unbalanced pressures and suggested some expensive work arounds. I doubt though that he is thinking of spending £1-£2k just to replace his bathroom taps.
I have never used them but there is a "balancing" valve which seeks to balance the cold water pressure with the dynamic hot water pressure. they are quite expensive but I have never used one but have seen people on here say they work.
WATER PRESSURE EQUALISING VALVE
Equalises hot and cold water pressure by automatically adjusting the higher water pressure to balance with the lower. Easy to install and ideal for shower mixers, bath/shower mixers, single lever mixers, bidet mixers. The mixer must be designed to operate on equal pressure. The valve will equalize pressure on multi-point/combi or fully modulating gas boilers, gravity systems, mains pressure hot water cylinders, or any hot water system which provides constant temperature output.
DIMENSIONS :
100 mm long x 75 mm wide x 60 mm deep.
Thread : 1/2" BSP Male on all inlets and outlets.
Nuts and olives not supplied.
Working pressures :
minimum 20 kPa, 0.2 bar (3 p.s.i.)
maximum 1,000 kPa, 10 bar (150 p.s.i.)
For nuts P/N 6744 and olives P/N 6750 please click here.
Thats from the BES catalogue.
What works in one installation may not work in another.
A plain pressure reducing valve on the cold feed should also work. Again I have never used one myself and have not heard of them being used although they are the obvious simple first choice.
If the mains pressure is over about 1.5 Bar then two in series may be more satisfactory as they work better with a lower reduction ratio. Most cheap ones seem to have a minimum output pressure of 0.5 Bar and in most bungalows about 0.2-0.3 Bar would be more appropriate.
Tony
You have pointed out the pitfalls of unbalanced pressures and suggested some expensive work arounds. I doubt though that he is thinking of spending £1-£2k just to replace his bathroom taps.
I have never used them but there is a "balancing" valve which seeks to balance the cold water pressure with the dynamic hot water pressure. they are quite expensive but I have never used one but have seen people on here say they work.
WATER PRESSURE EQUALISING VALVE
Equalises hot and cold water pressure by automatically adjusting the higher water pressure to balance with the lower. Easy to install and ideal for shower mixers, bath/shower mixers, single lever mixers, bidet mixers. The mixer must be designed to operate on equal pressure. The valve will equalize pressure on multi-point/combi or fully modulating gas boilers, gravity systems, mains pressure hot water cylinders, or any hot water system which provides constant temperature output.
DIMENSIONS :
100 mm long x 75 mm wide x 60 mm deep.
Thread : 1/2" BSP Male on all inlets and outlets.
Nuts and olives not supplied.
Working pressures :
minimum 20 kPa, 0.2 bar (3 p.s.i.)
maximum 1,000 kPa, 10 bar (150 p.s.i.)
For nuts P/N 6744 and olives P/N 6750 please click here.
Thats from the BES catalogue.
What works in one installation may not work in another.
A plain pressure reducing valve on the cold feed should also work. Again I have never used one myself and have not heard of them being used although they are the obvious simple first choice.
If the mains pressure is over about 1.5 Bar then two in series may be more satisfactory as they work better with a lower reduction ratio. Most cheap ones seem to have a minimum output pressure of 0.5 Bar and in most bungalows about 0.2-0.3 Bar would be more appropriate.
Tony
I've used a couple and they work but if the water is hard the length of time they work for is short.
Hi dreadnoughtheating-Agile-vulcancontinental thanks for the replies but it seems nowadays just to replace a shower mixer tap is near to taking a degree in science,what happened to the days of buying a tap and fitting it,Im begining to feel like giving up on the idea, Thanks all
M
mysteryman
That could be why you need a competent plumber.
Don't just change the bath taps for a shower mixer with gravity hot and mains cold - it will be nothing but grief.
Don't just change the bath taps for a shower mixer with gravity hot and mains cold - it will be nothing but grief.
Like everything in this world when you get something more compl;icated then it becomes less reliable and complications arise.
Walking is VERY reliable !
Cycling brings punctures and broken chains.
Cars being punctures, broken cam belts and enginene faults.
Space shuttles dont get punctures but suffer from broken "O" rings, failed insulation and oxygen tanks bursting.
Walking is VERY reliable !
Cycling brings punctures and broken chains.
Cars being punctures, broken cam belts and enginene faults.
Space shuttles dont get punctures but suffer from broken "O" rings, failed insulation and oxygen tanks bursting.
G
Goldspoon
I see a need for a NON mixer tap that fits via a single hole basin. Two taps on a single unit where the flexis run through a single hole. Anybody seen one?
A kitchen tap with a single spout contains that arrangement as the spout is coaxial ( on most anyway ) and there is no mixing within the tap so it works fine on mixed pressures.
Many however have very small tappings and dont give much flow as they are designed for rest of world places where they dont have loft tanks.
On the worst case of mixed pressures that I have seen when you turned on the hot tap water came out. If you then turned on the cold tap it stopped all flow from the mixer tap and instead forced the flow into the loft tank.
Tony
Many however have very small tappings and dont give much flow as they are designed for rest of world places where they dont have loft tanks.
On the worst case of mixed pressures that I have seen when you turned on the hot tap water came out. If you then turned on the cold tap it stopped all flow from the mixer tap and instead forced the flow into the loft tank.
Tony
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Can you not get a bi flow mixer.
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