Adding a booster pump to a secondary system

[SmithO]

Hi, thanks for reading post.

I’m working in a large house which has 3 upstairs bathrooms all with showers and baths. Hot water pressure is very poor so looking to add a booster pump to the hot side. Cold is taken from mains to all bathrooms.

Have added booster pump to system and turned off secondary system pump and valves so no hot water should be returning back to cylinder. But the pump is constantly on and pressure indicator on cylinder is showing large fluctuations. Struggling to trouble shoot why water still returning back to cylinder.

System is quite old so could secondary system valves be perished? There is one immediately before and after the brass pump?

Any advice greatly appreciated. I have a small building contract company, and customer wants us to increase hot pressure.

Many thanks.

 

[Welder]

I've been thinking about this and wouldn't his booster pump continually run as it won't be able to charge the cylinder up?

Craig - you're offically a genius

The pump runs continually because it's NOT on a closed circuit. As it uses a pressure switch the system can never pressurise! The booster needs to be operated via a flow switch instead. This means that when a tap is opened the pump will kick in.

HOWEVER. The brass circulator talked about (I suspect will actually be a bronze pump suitable for circulating heavily oxygenated water) will need to be reinstated and run at approx half the flow rate of the boost pump (possibly with some for of bypass) so as not to start the boost pump. If you don't have the circulator running you will waste literally loads of water everytime a tap is opened before you get any hot water anywhere and this will pi55 em off greatly.

 

[Aire]

Craig - you're offically a genius

The pump runs continually because it's NOT on a closed circuit. As it uses a pressure switch the system can never pressurise! The booster needs to be operated via a flow switch instead. This means that when a tap is opened the pump will kick in.

HOWEVER. The brass circulator talked about (I suspect will actually be a bronze pump suitable for circulating heavily oxygenated water) will need to be reinstated and run at approx half the flow rate of the boost pump (possibly with some for of bypass) so as not to start the boost pump. If you don't have the circulator running you will waste literally loads of water everytime a tap is opened before you get any hot water anywhere and this will pi55 em off greatly.

Is it actually possible to have a secondary circuit and boost pump together? You can turn the circulator down so it doesn't activate the flow switch, but once a taps opened won't water just flow down the secondary circuit anyway constantly keeping the flow switch activated?

 

[Welder]

Is it actually possible to have a secondary circuit and boost pump together? You can turn the circulator down so it doesn't activate the flow switch, but once a taps opened won't water just flow down the secondary circuit anyway constantly keeping the flow switch activated?

Most circulators run on a timer to be fair to avaid undue energy wastage. No, the circulator flow should have a mech non return so that shouldn't happen. What may happen tho is that the boost pump might be slow to turn off. To minimise that issue, personally I'd put an interlock in place so that when the boost pump runs it shuts off the circ pump and keeps it off for a couple of minutes till things settle.

 

[JVTrades]

From my point of view there is no need to take secondary pump out as this simply circulates water between the cylinder and wherever it's connected into the pipework and provide hot water quicker pumped or otherwise. At the least I would fit a none return and pressure reducing valve on the incoming water main matched to the output of the pump otherwise no unit requiring a balanced supply will work correctly. This is also a gamble as the cold mains pressure (unless extremely good) could be lower than the pump puts out at times. From the sounds of it, the bathrooms are old and probably have single bath and basin taps in which case no issue.

I agree that there is a lot more info required as there are quite a few variables.

Sometimes things just can't be done properly without spending a lot of money.

 

[SmithO]

Hi guys, thanks for replies. I have some pics now. Mains pressure is very good. Excuse the plastic pipe work down to the pump, this has been run temporarily and will be run in copper and dressed to wall accordingly on the new year. (If it needs to stay. I.e. plastic is temporary to see if working).

The boilers and this cylinder are housed in a separate boiler room. I have included a couple of other pics to show this.

 

[Riley]

That’s a shower pump yeah???

 

[Riley]

What is the incoming mains pressure flow etc

 

[ShaunCorbs]

This isn't a house

Guess hotel

 

[ShaunCorbs]

If the gauge is correct you have 70m of head pressure on the cylinder

 

[Riley]

Three boilers one cylinder something doesn’t add up

 

[SmithO]

It is a house, 3 upstairs bathrooms, kitchen and WC.

Have tried to Include video of hot water running pressure but won’t let me upload.

Incoming mains pressure is very good, and there are two large water storage tanks in attic. House has 2 floors.

 

[ShaunCorbs]

It is a house, 3 upstairs bathrooms, kitchen and WC.

Have tried to Include video of hot water running pressure but won’t let me upload.

Incoming mains pressure is very good, and there are two large water storage tanks in attic. House has 2 floors.

What's the sq foot of this house

As your heating boilers are a min of 70 kw each x 3 that's a lot of heat for a small house

 

[SmithO]

Three boilers one cylinder something doesn’t add up

The three boilers run a large Manor House and a Coach house. Manor House is 11,000 sq ft and coach house is 3,500 sq ft. The boilers just run the central heating for the Manor House, Coach house and hot water for coach house.

Manor House has its own hot water system, separate to this and in the Manor House, rather than the boiler room.

 

[SmithO]

2 boilers are only running at present also rather than all 3

 

[ShaunCorbs]

So your in the coach house ?

 

[SmithO]

That’s correct Shaun.

 

[Riley]

Put in a correctly sized unvented

 

[SmithO]

You are correct and that is what want to do in the next couple of months. Just need to see how can get hot water pressure up with what have at the minute.

 

[Riley]

Would say surely you don’t have the current capacity for three bathrooms??

 

[ShaunCorbs]

Your problem now is stored hot water

What's the cylinder size

And are you heating via top immersion?

 

[Welder]

Somethings not right. Bits of info & patently not plumber nor idea so I'm out.

 

[SmithO]

Your problem now is stored hot water

What's the cylinder size

And are you heating via top immersion?

No, heating via boiler. Immersion is on at minute but has just been turned off when taking pics.

 

[rpm]

Somethings not right. Bits of info & patently not plumber nor idea so I'm out.

I think the butler did it!

 

[SmithO]

Somethings not right. Bits of info & patently not plumber nor idea so I'm out.

What extra info do you want Dave?

 

[SmithO]

I think the butler did it!

 

[Riley]

I think the point is this doesn’t add up. The cylinder that we’ve seen the top of will not have the capacity to feed three bathrooms I can’t believe this has ever worked

 

[Riley]

Are you a plumber?

 

[SmithO]

Are you a plumber?

No, and have never pretended to be on here. I have a building contract company and have a plumber that is away over Xmas. Needed to see if I can get hot water pressure in short term before putting in an invented system.

Will the cyclinder not work due to the capacity?

 

[SmithO]

Have answered every question that has been asked. Just looking for some advice.

Many thanks.

 

[ShaunCorbs]

Should be fine if you run one bathroom at a time but won't last with all 3 going at the same time less than 5 mins on full load