Pumped HW

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mibazza

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Aberdeenshire
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United Kingdom
Hi,

I live in Scotland,UK and have a flat roofed house and my hot water cylinder is in the cupboard of one of the upstairs bathrooms giving a very low head of HW pressure to my two upstairs bathrooms (and low pressure downstairs too). My CW is mains pressure. What I would like to do is fit a single connection pump to boost the HW pressure coming off the cylinder. Both of my showers are electric, cold feed only showers. My washing machine and dishwasher are also cold feed so I can't see a problem with the HW & CW pressures being out of balance. Although they are already massively out of balance and I'm trying to bring them closer to equal (CW is 1 bar static pressure and about 0.7 bar dynamic, just barely enough for our electric showers). The main reason is that my 3 year old son has a bath every other night and it takes about 30mins to fill the bath barely with enough hot water to bathe him. I'm hoping to power the pump from the spur in the cylinder cupboard which feeds the electric heating element in the HW cylinder as it is never used so I will disconnect it, the cylinder is heated primarily from the central heating system. I realise I will lose the backup function of the electric heating element but I'm ok with this. I will also change the MCB for the electric heater to a suitable rating for the pump.

Any advice please on whether this sounds like a reasonable idea?
 
It is depend on what size cold water tank is.

Too small and the pump will run it dry if the ballvalve can't keep up with fill water.

Where is the tank?

Daniel.
 
The header tank that fills the HW cylinder is on a shelf directly above the cylinder in the same cupboard. But I can fill a bath without draining all the hot water, so I wouldn't run the header tank dry? The cylinder may run low tho. But as it's heated indirectly from the central heating would this matter? Surely all pumps are installed to gravity systems where the pump will supply quicker than the mains CW can re-fill?
 
1. Fit a combi boiler.
or 2. Fit an unvented hot water cylinder to give mains pressure hot water in the house.
I would try the immersion heater to heat the hot water tank. Sounds like for some reason the cylinder isn't getting
fully heated.
Don't mess about with pumps.
 
dcawkwell said:
1. Fit a combi boiler.
or 2. Fit an unvented hot water cylinder to give mains pressure hot water in the house.
I would try the immersion heater to heat the hot water tank. Sounds like for some reason the cylinder isn't getting
fully heated.
Don't mess about with pumps.
Click to expand...
What a load of rubbish.

Why would someone with such terrible cold water pressure fit a combi? Or even worse.. an unvented cylinder?!

You have even misunderstood the problem; he has plenty of hot water, the flow rate is just poor.
 
Wow thanks, I hadn't thought of replacing the entire system.......waste of time. I'll wait and speak to a real plumber for advice rather than armchair know-it-alls. For the record I appreciate the first reply, I've looked into what you say and understand it now, I'll need to come up with a better solution. To the last reply, maybe I'll just buy a new house with a better plumbing system and more water pressure? Simples.
 
I've seen a website called showerpowerbooster or something like that, claims to boost pressure from 12v supply? I'm sceptical about it and there are no figures quoted for it, but I'm only looking to fill the bath quicker with hot water at the end of the day. Anyone seen these in action?
 
I am a real plumber!
Your mains pressure is fine if a little low. Your hot water press is poor because of the configuration.
True you can improve this with a pump but expensive and noisy. Better to chuck the lot out and do it with something modern.
A combi will give you unlimited hot water at mains pressure 1 bar. You don't mention the flow rate you are getting.
I have 1 bar mains pressure with a unvented cylinder and it works fine no messing about with pumps header tanks etc.
Join the 21 century.
 
St0rmer66 said:
dcawkwell said:
1. Fit a combi boiler.
or 2. Fit an unvented hot water cylinder to give mains pressure hot water in the house.
I would try the immersion heater to heat the hot water tank. Sounds like for some reason the cylinder isn't getting
fully heated.
Don't mess about with pumps.
Click to expand...
What a load of rubbish.

Why would someone with such terrible cold water pressure fit a combi? Or even worse.. an unvented cylinder?!

You have even misunderstood the problem; he has plenty of hot water, the flow rate is just poor.
Click to expand...

Because pressure does not matter flow rate does!
The flow rate is poor because of the low pressure hot water header tank. Probably blocked feed or just not enough head of water.
Good grief.
 
mibazza said:
I've seen a website called showerpowerbooster or something like that, claims to boost pressure from 12v supply? I'm sceptical about it and there are no figures quoted for it, but I'm only looking to fill the bath quicker with hot water at the end of the day. Anyone seen these in action?
Click to expand...
Only seen one once. He had some sort of Master and slave pump in series if I remember correctly. Anyway he seemed very happy with it and was very easy to fit. Only a low hum of noise but obviously not quite on the same level as a shower pump in terms of output!
 
dcawkwell said:
St0rmer66 said:
dcawkwell said:
1. Fit a combi boiler.
or 2. Fit an unvented hot water cylinder to give mains pressure hot water in the house.
I would try the immersion heater to heat the hot water tank. Sounds like for some reason the cylinder isn't getting
fully heated.
Don't mess about with pumps.
Click to expand...
What a load of rubbish.

Why would someone with such terrible cold water pressure fit a combi? Or even worse.. an unvented cylinder?!

You have even misunderstood the problem; he has plenty of hot water, the flow rate is just poor.
Click to expand...

Because pressure does not matter flow rate does!
The flow rate is poor because of the low pressure hot water header tank. Probably blocked feed or just not enough head of water.
Good grief.
Click to expand...
Ever heard of diminishing returns? For the thousands he would have to spend that you suggested the only benefit would be his bath filling a little quicker. He has electric showers throughout so the new boiler and/or cylinder would have no effect what so ever on those.

A pump might cost a couple of hundred and fix the only problem he has with his current setup.

0.7 bar dynamic and you suggest an unvented... Crazy. He'd be better moving the tank into the loft if that's an option and staying vented but not likely if it's flat roofed.
 
Last edited:
Flat roof, no loft. I am planning to join the 21st Century just not for a few years until I rip the house to bits and redcorate it and upgrade it all at once, it was built in the 1800's with 2ft thick granite walls and theres not much thats 21st century at the moment. I take onboard the comment about me wanting more flow not pressure. The header tank can't go higher than it is as it's at the roof basically. So do I have any other options to imrove flow to the hot tap at the bath before I upgrade the whole lot? When I upgrade I'm planning to go unvented with mixer showers but cold mains pressure might be an issue there too.
 
A pump will do, provided there is no possibility of the header tank becoming empty. If it does, air will be sucked into the pump and it will be destroyed.
If the header tank is a decent size and you are not intending to fill the bath to overflowing, this should not be an issue.
 
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