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.

 

[Rob Foster]

Have a look at the Shower Power Booster, its ideal for this application easy to fit. Look up Alan Hughes or Flowflex
centralheatking

 

[king of pipes]

A picture of what you have done will help bud , have you mixed the stored cold water via the CWST to feed the cylinder and then cold water mains in the bathrooms to shower feeds etc? Kop

 

[SmithO]

Thanks for reply Kop. Not there over the weekend to get pic.
Have 2 large CWST in loft feeding cylinder, mains feeds cold taps etc in bathrooms.

 

[SmithO]

Right Pump 120 SU Pumps | Salamander Pumps

Link to pump trying to install.

Had 35mm coming out of cylinder, reduced this to 22mm a fair distance from vent pipe, into pump, then 22mm out of pump back upto 35mm. Return flow for secondary comes back in 22mm. This has a gate valve, then brass pump then gate valve back into cylinder.

 

[Welder]

Have a look at the Shower Power Booster, its ideal for this application easy to fit. Look up Alan Hughes or Flowflex
centralheatking

Sorry Rob must disagree. Alans product will not deliver what is reqd here. A pair need to be sited right before products they improving for best results.

 

[king of pipes]

Most likely your problem if no NRV fitted to shower mixers or mixer taps you could possibly get a back feed on the hotwater and the pump is sensing that . Kop

 

[SmithO]

Would that pump hot water back into the cylinder?

 

[king of pipes]

Could do yes

 

[Mark K]

Most likely your problem if no NRV fitted to shower mixers or mixer taps you could possibly get a back feed on the hotwater and the pump is sensing that . Kop

Isn't he only working with the HW, all cold feeds are mains? So any let by at taps or shower mixers caused by his pump would be into the mains? (That's another problem!)

If mains water pressure is good, the obvious answer is a non vented HW system.

But I'm struggling to decipher this...

"Have added booster pump to system and turned off secondary system pump and valves"

is he confusing primary, i.e. Heating Water with secondary, ie Hot Water. Can't think what pump and valves he is referring to on the secondary system if he is only now adding a pump.

 

[Aire]

Isn't he only working with the HW, all cold feeds are mains? So any let by at taps or shower mixers caused by his pump would be into the mains? (That's another problem!)

If mains water pressure is good, the obvious answer is a non vented HW system.

But I'm struggling to decipher this...

"Have added booster pump to system and turned off secondary system pump and valves"

is he confusing primary, i.e. Heating Water with secondary, ie Hot Water. Can't think what pump and valves he is referring to on the secondary system if he is only now adding a pump.

He's referring to a secondary return pump which he has now isolated because he's installed a single impeller booster pump to increase his hot pressure.

 

[Mark K]

He's referring to a secondary return pump which he has now isolated because he's installed a single impeller booster pump to increase his hot pressure.

Ah, I couldn't work that out! Cheers.

 

[Welder]

What I cannot work out is why the secondary return has been removed. They do different jobs completely! By putting a booster in it will still be some time before HW reaches the farthest point.

For the life of me I cannot work out what this system consists of based on the posts. I need a drawing or comprehensive pictures before I'll comment.

 

[Aire]

What I cannot work out is why the secondary return has been removed. They do different jobs completely! By putting a booster in it will still be some time before HW reaches the farthest point.

For the life of me I cannot work out what this system consists of based on the posts. I need a drawing or comprehensive pictures before I'll comment.

I'm guessing he believed the water flow from the secondary pump might activate the booster pump, maybe he's not aware the pump he's fitting relies on a pressure switch, not a flow switch.

What's also confusing me, is he says the pressure gauge on the cylinder is showing large fluctuations, why would a gravity fed cylinder have a pressure gauge?

 

[Welder]

I'm guessing he believed the water flow from the secondary pump might activate the booster pump, maybe he's not aware the pump he's fitting relies on a pressure switch, not a flow switch.

What's also confusing me, is he says the pressure gauge on the cylinder is showing large fluctuations, why would a gravity fed cylinder have a pressure gauge?

I share your concern of too little plumbing knowledge t9 help us diagnose correctly.

 

[king of pipes]

Think we are in agreement chaps pictures are needed but still think the cold mains is possibly overcoming the hot supply could be wrong . Kop

 

[Welder]

Think we are in agreement chaps pictures are needed but still think the cold mains is possibly overcoming the hot supply could be wrong . Kop

Hmm. In that large empty space tween my ears, I'm thinking that if incoming main is pressurising hw system then the pressure sensor on the pump would be satisfied and the pump would stop. If however the incoming pressure is lower than that produced by the pump and there exists a defective (or missing) NR in the cold supplies to showers etc then the pump would run continually and a gauge (cant work out where that would be fitted) would fluctuate.

If the last case then the defective NR would be findable as the cols supply pipework from (to) the shower would be warm. All very very very non compliant tho...

 

[SmithO]

Hi, Craig is correct. I have isolated the secondary pump because believe that would kick in the booster pump.

The cylinder is very old and there are two gauges on top of the cylinder, temperature gauge and a pressure gauge. The system is in a coach house boiler room that supplies a main Manor House. The Hot water system only supplies the coach house. The Manor House has separate pumps etc.

It is a gravity fed system. I will draw a diagram and get this posted ASAP.

 

[SmithO]

I have found an older photo of gauges and also a diagram. My drawing is worse than my plumbing, apologies

 

[Welder]

Oh dear. Is the pump shown in the drawing the one youve installed?

 

[Riley]

Hmmm intersting

 

[SmithO]

Oh dear. Is the pump shown in the drawing the one youve installed?

Yes

 

[Welder]

Yes

Okay. Def detailed pics reqd before we move forward.

 

[SmithO]

Ok. What were your thoights when saying oh dear??

 

[Riley]

Pics please as it could be a proper cock up

 

[Welder]

Ok. What were your thoights when saying oh dear??

Lets just wait for pictures.

 

[SmithO]

Will get some posted tomorrow.

 

[ShaunCorbs]

going off that i would say one big building

 

[Welder]

going off that i would say one big building

With a def need to circulate the HW to get a reasonable response. Especially as already used to it!

 

[Aire]

With a def need to circulate the HW to get a reasonable response. Especially as already used to it!

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?

 

[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.