Pump for pressurising system

2011

Hi plumbing experts!
Please help

So my sister has a standard two storey house with a old gas boiler. Tank in the attic as normal. It has a pump for the shower in the hot press to pressurise the hot and cold feed to the shower.

Then she engages with a plumber. He recommends installing a air more effiicient Ideal Logic combi boiler. She goes with his recommendation as well as renovating the downstairs bathroom.

End result:
New combi boiler installed.
Existing shower pump and hot water cylinder are removed.
Bathroom renovated, new toilet, wash hand basin, shower added.
New pump to pressurise the system is installed.



Problem:
The pump that has been added without any prior discussion runs every time any water is used. This includes flushing a toilet, using the washing machine or a wash hand basin. It is noisy and starts and stops many times per hour. Unfortunately it has been installed in the hot press which is practically in one child's bedroom and right beside two other bedrooms. So the issue is nobody can sleep.

A number of years ago we got a Potterton combi boiler installed in my mother's house. It was a great success, no issues, no pump running unless you have a shower. This house is a bungalow so the head pressure from tank in the attic is even less.

So my questions are:
1) I appreciate that it will be necessary to pressurise the water to the shower (or it will just be a trickle), however is it really necessary to pressurise everything else? There were no issues with water pressure in the past, the tank in the attic provided sufficient pressure. Is this a way of resolving an issue of pipes being under sized? Or is this driven by the make of boiler that was selected?

2) Can the pump be relocated and still work?

3) Can you offer some advice?

Many thanks, 2011

2011

Update: Plumber claims that the pump is required because the house has a ½" mains supply pipe. This makes no sense to me as the demand has not changed. He also claims that combi boilers require a higher pressure than other boilers and that the pressure from the tank in the attic is insufficient.

Sleeper12

All I do is showers nowadays so I'm no expert on boilers.

I'm not a big fan on combi boilers that work off the mains. I'm old fashioned and I like to see the attic tank being used.

Does this boiler run off the attic tank? Sounds like it does yet plumber complaining about a half inch mains feed & that might suggest its mains fed.

If it were my house and the bathroom was being renovated anyway I would have brought a separate supply from the attic tank to the toilet. This would have kept it off pump


It's not my field at all but changing the pump will make a huge difference. I've a Stuart Turner's monsoon 3 bar & it whispers. Brass body pumps are much quieter than plastic body. A timer on the pump for late night flushing will be a big help.

2011

Sleeper12 wrote: »

I'm not a big fan on combi boilers that work off the mains. I'm old fashioned and I like to see the attic tank being used.

I don’t know think that this one works of the mains to be honest. I assumed that all boilers worked of a tank on the attic as this pressure is constant as it is not exposed to external influences.

Does this boiler run off the attic tank? Sounds like it does yet plumber complaining about a half inch mains feed & that might suggest its mains fed.

I need to establish this.

If it were my house and the bathroom was being renovated anyway I would have brought a separate supply from the attic tank to the toilet. This would have kept it off pump

Makes sense. Plumber claims that the cystern (he selected) requires high pressure to fill within a reasonable timeframe and this can only be achieved with a pump.

Dardania

It isn't really necessary to pressurise everything else - possibly just the WHB cold (so as to balance the pressure coming in for the hot). The toilet and washing machine could easily run from the cold water tank directly (and in fact, in the case of toilet, that would be best in case there's a power cut so as it fills in a reasonable time) - similar to sleeper12's point.

The issue with achieving that aim is how the pipework is configured, and the ease of getting a separate supply to the washing machine & toilet. It might be a pain to intercept the pipework.

As sleeper12 also mentions, improvements could be made at the pump end. Replacing pump might be drastic, until you check for the Use of flexible hoses, which is good to prevent vibrations reverberating via pipework, and if there's some way of isolating the feet from the floor (pump shouldn't be screwed to the floor)

Regarding your update from the plumber, everything mentioned makes sense. Combi boilers should be run from the attic via a pump, rather than directly from the mains. The pressure available at the flowrate demanded for a shower is not adequately deliverable from a 1/2"main. The issue isn't so much the demand, as the buffering of the supply in order to meet the demand.
Previously the shower was fed from the attic and had it's own pump to pressurise the supply. Now the same configuration is in place, except the shower & pump are separate. I'm sure also that the shower now installed delivers higher flow than the previous one.

One thing to check - does the pump start and stop frequently, without any water demand? If so, it suggests there's a leak somewhere... Also, does the pump have an expansion vessel on top of it - see item C in the linked: https://www.dabpumps.com/sites/default/files/2016-03/BOOSTER%20SILENT_TS_ENG.pdf That can help smooth out the frequent start / stops somewhat.

rightjob!

Is there a pump matt under the pump or just placed directly onto the timber floor?

Best option when doing this is to make a bracket off the gable wall and put the pump on that with a pump matt.

You wont hear it then..

If the pump is running while you have the washing machine on i would change that feed to a mainsfeed.

2011

Dardania wrote: »

It isn't really necessary to pressurise everything else - possibly just the WHB cold (so as to balance the pressure coming in for the hot). The toilet and washing machine could easily run from the cold water tank directly (and in fact, in the case of toilet, that would be best in case there's a power cut so as it fills in a reasonable time) - similar to sleeper12's point.

Here is how it looks to me (speaking as a non-plumber):
There is a 3/4" copper pipe in the hotpress fed from the water tank in the attic. This pipe feeds the pump and the pump feeds everything else (boiler, toilets, washing machine, wash hand basins etc....)

The issue with achieving that aim is how the pipework is configured, and the ease of getting a separate supply to the washing machine & toilet. It might be a pain to intercept the pipework.

Well the opportunity to replace everything was provided. Extensive works are being carried out throughout the house, including the removal of walls, plastering, rewiring, new bathroom etc. I would expect a good plumber to offer the various options, explain the pros and cons and provide costs for each option.

As sleeper12 also mentions, improvements could be made at the pump end. Replacing pump might be drastic, until you check for the Use of flexible hoses, which is good to prevent vibrations reverberating via pipework, and if there's some way of isolating the feet from the floor (pump shouldn't be screwed to the floor)

Yes, these are all being explored. The problem is that we were never informed of the requirement for the pump, the first we knew of it was after it was installed. The location for the pump is not suitable. A better location (less convenient) has been identified, we plan to move the pump there. This is in the attic of the single story extension which will be well away from bedrooms and the other side of a block wall.

Regarding your update from the plumber, everything mentioned makes sense. Combi boilers should be run from the attic via a pump, rather than directly from the mains.

Not in every case as far as I know. We did get a combi boiler installed in my mother's house a number of years ago. I think it is fed from the mains. The only time a pump runs is when the shower is used (we have no issue with this). Obviously a small circulation pump is also required for the rads.

The pressure available at the flowrate demanded for a shower is not adequately deliverable from a 1/2"main. The issue isn't so much the demand, as the buffering of the supply in order to meet the demand.

Correct, I know this already.

Previously the shower was fed from the attic and had it's own pump to pressurise the supply. Now the same configuration is in place, except the shower & pump are separate. I'm sure also that the shower now installed delivers higher flow than the previous one.

Pretty much the same pressure as before to be honest.

One thing to check - does the pump start and stop frequently, without any water demand? If so, it suggests there's a leak somewhere...

It does, we suspect a leak, told plumber already.

Also, does the pump have an expansion vessel on top of it

Yes, but it does very little to reduce the on/off switching of the pump. Perhaps the pressure is low.

There is nothing wrong with what you had before and you could still fit a cylinder with the boiler you have and revert to gravity fed stored hot water which can be a better fit at times.