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Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Right then, need some advice please, ill detail the system first and then explain the problem.

We have a 50 gallon cold tank in the loft, this has a 28mm feed down to a 60 gallon hot water cylinder on first floor, this is connected to the shower pump via a 22mm feed. There is a 28mm feed also going down to the cold side of the shower pump (steeped down to 22 to enter pump) from loft tank. From the pump both pumped outlets come out of the top in 22mm then arch over and go down into the floor to route round to the bathroom. Once in the bathroom they come up into a stud wall where they tee off into 2 separate shower control valves to feed shower cubicle on one side and bath and shower on the other side. Feed into valves is 22mm, out of valves to shower/bath connections is 15mm.

The shower pump is a salamander rhp100 3bar pump, requires 1 litre per min water flow to trigger pump.

The shower valves are hudson reed 2bar min thermostatic diverter valves. These feed run of the mill bath filler and drencher + handheld showers.

The cold tank is set at the front of the house so has a 5m horizontal run before it drops into first floor, from the pump into bathroom is prob another 4m horizontal run.

Hot water cylinder is quite tall so head over outlet on this is prob only 70-80cm. Head over shower control valve is prob 1.5m, head over bath filler as lowest outlet is prob 2.1m.

Problem - all worked fine for the first week or so, switch on an outlet and pump kicked in straightaway all working great. Then one day it wouldnt work at all, eventually with a bit of jiggling on the temperature control it started up again. But the next day it would not work at all, jiggling to no avail!

Decided to check the little mesh filters fitted onto the pump inlets, both clogged up a bit, cleaned and refitted it all. Worked just fine again, for that evening only!

Since then it has been hard to get started, has worked on and off with much jiggling of controls required.

When you switch an outlet on there is no immediate water flow, prob due to HP valves on a low pressure system (until pump kicks in), but it had previously triggered the flow switches despite this, now it does not.

On one occasion i have managed to get good flow without the pump switched on, but only from the two highest shower outlets on the system, still no flow from the bath filler at this point!

When managed to trigger the pump i have allowed a full tank of hot and cold to flow through to make sure all air is absolutely purged from system. The next day it wouldnt go again.

Lost with what to do now. Checked filters again, clean this time.

Why would it work fine for a week and not work now? This points to either air locking in the pipework, poss in the arches from pump outlets and down into floor? or to desensitising of the flow switches?

I can understand the head pressure being a factor in this system due to tall hot water cylinder and HP control valves. But this is a factor that has not changed since the system was working.

Any suggestions gratefully received.

Thanks, Jamie.

thescruff · Moderator Joined: 03 May 2003 Posts: 4314 Location: Bath

How have you connected the cylinder to pump pipework.

Sounds like you would have been better with a negative head pump.

The cold storage is undersized by at least half.

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Surrey flange (specified and made by salamander) connects cylinder to pump with 22mm pipework.

Neg head pump may have been better but was advised on pump choice by salamander tech, thats not to say they havent got it wrong though!

However im just puzzled as to why this would now have stopped working reliably when it did for the first week?

Cold water storage, do you mention this as it is relative to the problem i have here or just as a consideration of the way water will be consumed in this system?

thescruff · Moderator Joined: 03 May 2003 Posts: 4314 Location: Bath

Yes I mention it as a possible problem, for example if you were running out/low of storage water, which is a possibility with the draw-off you have, then air could be a problem.

I say a negative head pump because of the valves you have, they require a high pressure, an easy way to check is by turning the showers on with the pump turned off, if you have no flow then the pump flow switch will not kick the pump in.

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Point taken on the cold storage, will have to see if that is an issue at any point or not.

Will a neg head pump constantly maintain pressure on the bathroom side of the pump then when not engaged?

Still puzzled as to why it was fine for a week and now is not, thats gonna bug me til i get to the bottom of it. Any thoughts on that part of it?

Ta, Jamie.

thescruff · Moderator Joined: 03 May 2003 Posts: 4314 Location: Bath

Other than blocked filters in the pump/shower valves, and air being a problem no, I need to think about it some more. Rolling Eyes

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Thanks chap, lemme know if you have any further thoughts on it, if i can restore it to a reliable working system without changing parts itd be good. Will check filters again at weekend and redo pump commissioning procedures see if it helps.

What about his question please - Will a neg head pump constantly maintain pressure on the bathroom side of the pump then when not engaged?

AlanE · Posted: Thu Jan 10, 2008 10:18 pm Post subject:

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Thanks Alan.

So if a 3bar neg head pump was employed would it constantly maintain 3bar when stopped or a lower pressure?

Just wondering whether a constantly held 3bar would be likely to accelerate the chance of a leak springing in the future? Some of the plumbing is in poly pipe and there are a couple of speedfit connectors used in awkward areas, now hidden under a heated tiled floor, perhaps the worst place for a leak!

straker1966 · Joined: 06 Jan 2008 Posts: 164 Location: cambridge

have the shower valves got non return valves in em? i could tell you a sob story or two about trying to get tank pressure thru continental brassware which contain non return valves!

if the valves are surface mounted, id be looking at taking em off, and trying to blow thru the valves to see how easy it is.

AlanE · Posted: Sat Jan 12, 2008 8:02 pm Post subject:

thescruff · Moderator Joined: 03 May 2003 Posts: 4314 Location: Bath

It will hold 3bar untill an outlet is opened, whereas the pump will switch on at its pre-set low pressure, 2.5 bar I think.

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Thanks chaps, straker1966, dont know about non return valves, they are sunk into a tiled wall too so will not be doing any blowing through em, will have to ring manufacturer and ask them.

What thoughts on constant held pressure bringing on the early onset of leaks, particularly in the case of the push fit fittings used?

thescruff · Moderator Joined: 03 May 2003 Posts: 4314 Location: Bath

Jamie C · Joined: 16 Nov 2006 Posts: 68 Location: Essex

Thanks.