Can you recommend a universal pump?
- Thread starter Slim69
- Start date
Sponsored Links
You need a twin with cold converted to tank supply. Singles are for boosting pre-mixed H/C to an outlet. H&C should be of equal pressure for mixers to work properly.
This is a quote from the Stuart Turner website, for a 2.0 bar universal single impeller negative head pump:
'Ideal for boosting hot water service to a common mixer where the cold supply is mains fed.'
Am I reading this wrong? This suggests that it will be fine to pump hot and supply a mixer along with mains fed cold.
'Ideal for boosting hot water service to a common mixer where the cold supply is mains fed.'
Am I reading this wrong? This suggests that it will be fine to pump hot and supply a mixer along with mains fed cold.
Sponsored Links
If that's what the manufacturer sells it for then you can give it a try. What I'm saying is you can't guarantee equal pressures this way, but it's what you're happy with that counts.
you could try fitting a PEV (pressure equalising valve) on the mixer after the pump.
In fact, my mains pressure seems very high, so I was thinking of putting a mains pressure reduction valve on the entire system?.
I could then ensure a common 2.5 or 3.0 bar pressure to both hot and cold, which should be ample for my purposes. The mixer bar I'm using, however, has an operating range of 0.1 - 5 bar on each input and apparently doesn't rely on equal pressures.
Where would I put the PEV exactly and what effect would it have? I'm planning on putting the pump on the hot before the mixer.
Also, I have another question. I was planning on using a techflow essex flange for my dedicated hot supply, but on investigation it looks like a dedicated supply to feed hot to the whole bathroom has already been tee'd off from the 28mm hot outlet off the top of the cylinder. Is there much benefit from re-doing it with the techflow or is it just extra work for not a lot in return?
And, last one, what exactly is the reason for needing a dedicated supply? Is it greater risk of airlocks or something?
I could then ensure a common 2.5 or 3.0 bar pressure to both hot and cold, which should be ample for my purposes. The mixer bar I'm using, however, has an operating range of 0.1 - 5 bar on each input and apparently doesn't rely on equal pressures.
Where would I put the PEV exactly and what effect would it have? I'm planning on putting the pump on the hot before the mixer.
Also, I have another question. I was planning on using a techflow essex flange for my dedicated hot supply, but on investigation it looks like a dedicated supply to feed hot to the whole bathroom has already been tee'd off from the 28mm hot outlet off the top of the cylinder. Is there much benefit from re-doing it with the techflow or is it just extra work for not a lot in return?
And, last one, what exactly is the reason for needing a dedicated supply? Is it greater risk of airlocks or something?
I was planning something similar at my house.
Came to the conclusion that for the shower, it was far far simpler to have the shower on low pressure.
i'd take a cold tank feed (low pressure) and a hot feed (still low pressure) and try a low pressure thermostatic shower mixer on it.
If that didn't work i'd add a pump inline for the hot and cold.
Thermostatic mixers normally have a maximum pressure difference from the supply's of 5:1, so 3 bar main into 0.1bar hot doesn't go, its 30:1
The bath i've got seperate taps, no issue of pressure mixing and passing through the tap into the HW cylinder.
The basin i've got a mono mixer, have got a PEV valve for this, it should bring the mains pressure down to same as the low pressure hot water, flow will be affected but not a big issue for hand washing.
the PEV also has non return valves in it to stop mains cold forcing its way through into the hot water cylinder and up into the loft.
http://salamanderpumps.co.uk/WebResources/Documents/Installation_Guidelines_Oct2011_Issue14.pdf
Have a read through the above.
i'm currently about to cheat and put a combi in, mains pressure hot and cold, no big problems in pressure difference
Main reason for dedicated feed for the pump is to prevent air ingress and cavitation, cavitation occurs when the water is subjected to low pressure or vacuum situations, such as the pump "sucking" on the hot pipe, happens worse on the hot as the water is closer to its boiling point.
It causes damage to the pump when it cavitates
Came to the conclusion that for the shower, it was far far simpler to have the shower on low pressure.
i'd take a cold tank feed (low pressure) and a hot feed (still low pressure) and try a low pressure thermostatic shower mixer on it.
If that didn't work i'd add a pump inline for the hot and cold.
Thermostatic mixers normally have a maximum pressure difference from the supply's of 5:1, so 3 bar main into 0.1bar hot doesn't go, its 30:1
The bath i've got seperate taps, no issue of pressure mixing and passing through the tap into the HW cylinder.
The basin i've got a mono mixer, have got a PEV valve for this, it should bring the mains pressure down to same as the low pressure hot water, flow will be affected but not a big issue for hand washing.
the PEV also has non return valves in it to stop mains cold forcing its way through into the hot water cylinder and up into the loft.
http://salamanderpumps.co.uk/WebResources/Documents/Installation_Guidelines_Oct2011_Issue14.pdf
Have a read through the above.
i'm currently about to cheat and put a combi in, mains pressure hot and cold, no big problems in pressure difference
Main reason for dedicated feed for the pump is to prevent air ingress and cavitation, cavitation occurs when the water is subjected to low pressure or vacuum situations, such as the pump "sucking" on the hot pipe, happens worse on the hot as the water is closer to its boiling point.
It causes damage to the pump when it cavitates
I think I'm going to run a cold supply from the cistern - I hadn't thought of doing this and trying the whole thing on low pressure first.
the only fly in that ointment is that my bath tap supplies are tee'd of the shower supplies. Will this cause a major problem, as they'll never be run at the same time.
the only fly in that ointment is that my bath tap supplies are tee'd of the shower supplies. Will this cause a major problem, as they'll never be run at the same time.
Not a problem running it all without a pump, get it plumbed in 22mm as much as you can.
the shower will need to stepped down to 15mm to fit normally but you could use a reducing tee off the bath feed for this.
if you decide you need a pump later, you should plumb the bath and shower separately as you don't need the extra pressure to fill the bath, using 22mm should be plenty of flow.
the shower will need to stepped down to 15mm to fit normally but you could use a reducing tee off the bath feed for this.
if you decide you need a pump later, you should plumb the bath and shower separately as you don't need the extra pressure to fill the bath, using 22mm should be plenty of flow.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
