Evening all
I'm refitting out our upstairs bathroom and adding in a new shower with a nice big chrome head coming out the ceiling. The pressure at the boiler (ground floor) is just below 2 bar and the mixer I need says 2 bar minimum so I need a pump. I don't have a tank in the loft so its all mains pressure driven and I intend to put the pump in the loft.

Looking online it looks like a twin regenerative positive pressure pump is right for me which I will site in the loft.
The reasons I have pick this is I want to get both cold and hot to the same pressure so they mix well, The regen type is said to cope with air in the system better and this is said to be an issue when above the tank. Finally I think positive pressure as I have about a bar of pressure in theory in the loft (5m up from boiler) where the pump will be.

Can anyone say if this is the right choice?
Also there are a lot of different makes out there starting at about £100 but I want it to last and above all I want it to be quiet so what make should I go for?

Cheers Pete

When you say 2 bar at the boiler, how are you getting that figure ?

Apologies in advance if i'm wrong, but are you by any chance reading the pressure gauge on the boiler?

Al.

Generally speaking you can't put pumps on mains fed showers - it is prohibited. The problem is that if the supply is off for any reason you can create a vacuum in the water main which could suck contamination through any weeping underground joints.
I'm pretty sure there is one pump that is certified for use this way, but 99% aren't.

It's my understanding too, you need to feed the pump from tanks, one hot tank, one cold. I'm probably wrong, but this ws the the set up I had....

I've just done the opposite thing - removed the pump and tanks! Reasons were simply based on the requirement to boil a tank of water, which I can only do electrically. It's also freed up a lot of loft space for more car junk. The shower is now a simple electrical 8.5 KW thing on mains pressure.

I don't know what to do with the Salamander pump (in perfect health), thinking of using it to pump an irrigation system (I store the water runoff in a huge underground tank), or put the thing on Ebay....

Thanks guys
looks like this is harder than I thought as I have no tanks in the loft and don't really want them if I can avoid it.

The mixers controls that I'm looking at say 2 Bar minimum so I'm a bit confused how to move forward have to talk to a plumber I guess.

cheers pete

???? i did try



i]Originally posted by watsonpj

I'm a bit confused how to move forward have to talk to a plumber I guess.

cheers pete

Sorry mate are you saying you are a plumber? If so what are my options? Is it just put some tanks in the loft?

cheers Pete

I should add that there is a very large hot water cylinder at the bolier but that's in the garage and the shower will be upstairs.

The house did have a shower in that room originally but it basically only worked when sitting and had very little flow out when standing.

cheers Pete

The only other problem I had (and another reason for removing the system) was that the old shower fitting and connecting pipework (not so carefully embedded into the lime rendered and mortared wall by the previous owner) ruptured... when one of those pumps gets a free head, it really does go for it!

I need more info......it now sounds like you might have an unvented cylinder ?

1- Why do you think you only have 2 bar water pressure

2- Does the cylinder have a name on it, is it white or silver rather than copper?

3- Is there an expansion vessel connected to the cylinder?

Or better still go take a photo of the cylinder


Originally posted by watsonpj
I should add that there is a very large hot water cylinder at the bolier but that's in the garage and the shower will be upstairs.

The house did have a shower in that room originally but it basically only worked when sitting and had very little flow out when standing.

cheers Pete

Thanks Wadders here the answers to the questions.

1- Why do you think you only have 2 bar water pressure - I had a expansion tank fail last year and when I refilled the system the gauge went up to just below the 2 bar mark on the refilling the system.

2- Does the cylinder have a name on it, is it white or silver rather than copper? MAIN 250L


watertank


3- Is there an expansion vessel connected to the cylinder? YEP

Or better still go take a photo of the cylinder

boiler

cheers Pete

Right, you have an unvented cylinder providing domestic hot water, which is mains fed, it will have a pressure reducing valve on the inlet which normally restricts the pressure to 3 bar ( The incoming mains water pressure will typically be 5 bar plus)

Forget any idea of using a pump with this system, it's not feasible and should not be necessary, 3 bar should give a powerful shower.

Ideally with an unvented cylinder you would run a balanced cold supply to the shower i.e take a cold feed from the 3 bar reduced cold rather than direct from the incoming main.

When you say the system was refilled to 2 bar, are you getting confused with the heating side ? Was it the red expansion you swapped ? If so that's for the central heating
Rather than domestic hot water, quite often there is no pressure gauge on the domestic hot water side.

If you are indeed only getting 2 bar hot pressure then you have something wrong which needs sorting out.

First check the incoming cold mains pressure and flow rate, you could have a problem with the supply to the house or a partially obstructed stop tap. ( do you have good pressure at the cold taps?

If this checks out ok I would suspect the pressure reducing valve to the cylinder could be faulty or blocked, some have a strainer in them which can be cleaned
But I've changed loads that are simply knackered inside and not giving out 3 bar. it's a combination valve which does a few things, so not cheap.


Al.

Thanks Wadders
Yes the 2 bar I get is at the boiler on the hot water side when I refilled the system but the whole system was drained at the time. The water comes in via a 3.5 bar prv and splits to supply all of the services, one way leading straight to the boiler via the 2 inline filler valves. If I open these up with the boiler cold and off (gauge at 1.5ish) the gauge rises to about 1.9bar max and doesn't go any higher. Doesn't this mean that the water pressure is only 1.9 bar or the prv is not working correctly and holding it at that.
Flow rate from the kitchen sink is pretty good at 1ltr in about 4 seconds. so over 12ltrs/min.

I guess I need to get a gauge on the supply before the prv and find out what it really is.

cheers Pete

Pete

Assuming the boiler gauge is accurate, and you've left the filling loop open for a decent period of time then yes it's possible that you only have 1.9 bar cold static pressure.

Only way to know for sure would be to fit a pressure gauge in the cold line after the 3.5 bar reducer, (there will actually be a tapping on the reducer designed for this purpose, but its normally blanked off.) or simply tee one in after the valve if easier.

I would expect 20 litres /min plus at the cold tap, if fed direct from the main but worth bearing in mind that pressure and flow rate are different things. usually the kitchen sink is fed direct from the mains, but yours might be a balanced supply i.e fed from the 3.5 bar reducer.

If you fit a gauge after the 3.5 bar reducer and it reads less than 3.5 bar you have a problem either with the reducer or the incoming main.

Gauges are really cheap, might be worth fitting two, one before the reducer and one after, at least then you will know which is causing the issue, the reducer or the main itself.

If you find its the incoming main, be prepared for a fight with your water supplier.

Al.





Originally posted by watsonpj
Thanks Wadders
Yes the 2 bar I get is at the boiler on the hot water side when I refilled the system but the whole system was drained at the time. The water comes in via a 3.5 bar prv and splits to supply all of the services, one way leading straight to the boiler via the 2 inline filler valves. If I open these up with the boiler cold and off (gauge at 1.5ish) the gauge rises to about 1.9bar max and doesn't go any higher. Doesn't this mean that the water pressure is only 1.9 bar or the prv is not working correctly and holding it at that.
Flow rate from the kitchen sink is pretty good at 1ltr in about 4 seconds. so over 12ltrs/min.

I guess I need to get a gauge on the supply before the prv and find out what it really is.

cheers Pete

Thanks Wadders
I'll look forward to fight with the water co as Im already in dispute with my gas/elec suppliers one that's meant to be supplying both and one that's only let go of one :-(.

cheers Pete

I've just had confirmation from Essex and Suffolk water that the water pressure in my area is between 1.8-2.5 Bar and I'm at the highest point in town or near as damn it so my 1.8-1.9Bar is about right at the boiler. So as my shower head is likely to be about 5m above so Im likely to be at about 1.2Bar. All the mixers etc say 1.6Bar plus so what do I do ?

If you have the space and deep pockets you could fit an accumulator system
http://hwch.myzen.co.uk/blog/category/water-boosting-accumulators/

Only other way i can think would be to fit a second gravity fed cylinder and cold storage tanks just to run the showers
bit extreme really, whoever specced an unvented cylinder in the first place must have been having an off day.

Al.





Originally posted by watsonpj
I've just had confirmation from Essex and Suffolk water that the water pressure in my area is between 1.8-2.5 Bar and I'm at the highest point in town or near as damn it so my 1.8-1.9Bar is about right at the boiler. So as my shower head is likely to be about 5m above so Im likely to be at about 1.2Bar. All the mixers etc say 1.6Bar plus so what do I do ?