Hot water boost pump.

[ukracer]

As per the title. I am posting a lot as SWMBO is cracking the whip before I hibernate into my work shop as I have threatened this year... Lol

I have just fitted a new set of taps in the kitchen but its not improved the flow as I hoped it might. It uses these micro bore connections they sell now.

Anyway I am wondering if a pump like this


Or perhaps a cheaper option

It does not need to give mega pressure just fill the washing up bowl inside 5 mins.

Oh yes I have downstairs hot water cylinder. I hope to have a combo boiler fitted in a couple of years so I don't wish to spend mega bucks.

 

[addjunkie]

If its a normal atmospheric hot water tank, pressure is driven by the head, height of the cold tank above

 

[WorkshopChris]

have just done a quick google search for that pump and the info is a bit vague. It looks like a modified central heating pump with a flow switch fitted, don't know how effective it would be.

 

[Bladevane]

MIRA used to supply a pump called the PS1. It was a hot water booster pump and came complete with flow switch. This switched the pump on when flow was detected. I believe the primary use was in houses which had been developed into the roof space where the head from the cold water tank was pretty small. Maybe someone else does a similar pump/switch unit. We have one in our upstairs shower room to supply hot water as described above and it works well.

 

[I'm getting on a bit]

https://www.salamanderpumps.co.uk

 

[mike os]

we only ever fit stuart turner pumps... bit more expensive but rarely fail, you can boost just the kitchen tap or all your hot taps ( and cold if they are fed from the tank)

 

[WorkshopChris]

we only ever fit stuart turner pumps... bit more expensive but rarely fail

If i have to specify a pump its always stuart turner, you cant get a better pump in my opinion.

 

[dobbslc]

Just a small single port shower pump will do it, I've got one in the eves supplying the upstairs sink tap, no power under gravity but really good with the pump, if anything it's too powerful!
This one has a reed switch that detects the water movement when you open the tap.
Try this link.
https://www.google.co.uk/search?q=t...&ved=0ahUKEwjBpYOPp4zWAhWRa1AKHQEpDYMQgTYI7AQ

 

[ukracer]

If its a normal atmospheric hot water tank, pressure is driven by the head, height of the cold tank above

And pipe diameter...... But I can't go any higher. or bigger.

 

[normspanners]

It does not need to give mega pressure just fill the washing up bowl inside 5 mins.

The problem is it DOES have to increase pressure to a fairly high pressure to overcome the stupid micro bore modern taps about 8mm they are mainly designed for modern combi boilers working on mains pressure old style systems dont have the pressure.
Central heating pumps are more of a circulating pump ie it is in a ring so that as it pushes the water away from the vane the other side is being forced into the vane by that same movement, where as a pure flow pressure pump picks up the water a forces it out of a open tap there is no circulation, so it is not feeding itself, it is a one way trip.

 

[normspanners]

And pipe diameter...... But I can't go any higher. or bigger.

pipe dia doesnt have any bearing on head pressure ------it increases flow yes------ not pressure.

 

[ukracer]

pipe dia doesnt have any bearing on head pressure ------it increases flow yes------ not pressure.

Its flow I need.

 

[normspanners]

Its flow I need.

Yes but larger pipes to the tap connectors wont improve the flow out of the tap because it has to pass through the micro bore of the tap, it is only pressure that can improve that flow , the micro bore is like having your tap half shut ALL THE TIME the ONLY way to improve it is to fit a proper high pressure pump into the system.
mains pressure can be 6-10 bar house internal water head possibly .5bar that is a massive difference.
10ft of water produces 4.3psi pressure.

 

[normspanners]

The sons combi boiler in his new house is fitted in loft above the kitchen ( stupid idea and his water main didnt have enough pressure to fill it ) he had 3/4 psi
I had to 'borrow' pressure from a neighbors house using their outside tap through two garden hoses to back pressure his system get the central heating working.

 

[Bladevane]

pipe dia doesnt have any bearing on head pressure ------it increases flow yes------ not pressure.

To a degree that is correct. Static pressure is a function of head alone. Dynamic pressure, when the tap is open, will depend on head and pressure loss along the pipe. So a small bore pipe will have greater losses.

 

[normspanners]

Static pressure is a function of head alone.

BUT ...the pressure will virtually be at head pressure right up to the tap headers though, changing pipe work will not alter that.

Dynamic pressure, when the tap is open,

is controlled by the micro bore of the tap headers.
The ONLY way to improve it, is to pump the system.

 

[Bladevane]

Exactly. The major flow restriction is the small bore pipe and probably the tap internals. Old fashioned multi-turn taps have a much lower pressure loss than the modern 1/4 or 1/2 turn ceramic taps.

 

[Rocketman]

BUT ...the pressure will virtually be at head pressure right up to the tap headers though, changing pipe work will not alter that.

is controlled by the micro bore of the tap headers.
The ONLY way to improve it, is to pump the system.

There is friction pressure loss as well to take into account. So fundamentally what you say is correct when not taking friction pressure loss into account but in a larger pipe there is less friction pressure loss.

https://en.wikipedia.org/wiki/Darcy–Weisbach_equation

Hence why it's not uncommon for large pipes to be implemented even though there is a restriction at the final point.

 

[normspanners]

Yes thank you I know about pipe friction losses, and the friction losses are greater the more the flow, but it pales into insignificance against 15mm reduced to 6-8mm micro bore !!
and again the only way top improve the flow is to pump it !!
no getting round it.
In fact you could make the pipes 22mm or bigger !! and it would not improve it in the slightest.

 

[Rocketman]

Yes thank you I know about pipe friction losses, and the friction losses are greater the more the flow, but it pales into insignificance against 15mm reduced to 6-8mm micro bore !!
and again the only way top improve the flow is to pump it !!
no getting round it.
In fact you could make the pipes 22mm or bigger !! and it would not improve it in the slightest.

You're welcome.