Any plumbing experts ?

[RogerS]

Rather bemused by 'events' in the new ensuite. Layout is as below.

Cold feed is fed by a 1 Bar pump. Hot water feed by a 3 Bar pump. The imbalance in pressure is not a problem anywhere else in the house systems.
The plumbing in the house is 'zoned' and each zone has its own gatevalve as per the photo

All pipework was pressure tested prior to plasterboarding, tile-backer board, tiling etc.

So, the moment had come. Turn on the gatevalves.
WC fills up, stops, flushes. No problem. No leaks.
Washbasin tap works ...hot/cold/or variation thereof. No problem. No leaks.
Time for a shower. Shower works fine. Turn it off. But the h/w pump continues to run...implying that it can't reach pressure ergo the water is still flowing somewhere.
Panic. Open up inspection hatch. No leaks.
Turn off H/W gatevalve. Pump stops.
Open H/W gatevalve. Pump starts up again. Where is the water going ?
Turn off C/W gatevalve. H/W pump stops. Que ?

Initial conclusion.. that the design of the Hans Grohe shower set is weird and that in reality OFF does not turn off the supplies but merely the feed to the shower head. The internals of the unit are 'live' and because of the higher H/W pressure, it backfeeds into the cold feed.

Proof of concept...turn temperature control on the Hans Grohe to as little hot water as possible. C/W gatevalve already on for this test. H/W pump stops. Then after ten seconds or so, starts up for a little bit then stops. Conclusion..the Hans Grohe temperature control doesn't fully close off the H/W supply.

Solution...double-check valve in the feed immediately after the C/W gatevalve.

So far so good ? All makes sense ? Well, it did until I thought wonder what happens if we turn off the C/W gatevalve, leave the Hans Grohe temperature control in the 'normal' position (ie if my theory holds..'live' connection between H/W and C/W) then if I turn on the washbasin tap in the Cold only position then the H/W pump should fire up and H/W come out of the tap.
Only it didn't.

OK..maybe there is some magic inside that mixer tap preventing this. Try the WC.
Flush the WC. That should also initiate a H/w pump start up. But it didn't.

So am totally confused.

Any experts ?

 

[sunnybob]

Point of order mr chairamn.... there are 4 BALL valves and 1 GATE valve in the picture. :lol:
OK, picky picky over.
There is a pressure switch that tells the pump to turn off. I suspect that switch is on the higher pressure system, and the lower hot water pressure just can not put enough pressure into the system to turn the switch off.
There isnt a leak, just an underpowered pump or over high set switch. 8)

 

[RogerS]

Point of order mr chairamn.... there are 4 BALL valves and 1 GATE valve in the picture. :lol:
OK, picky picky over.
There is a pressure switch that tells the pump to turn off. I suspect that switch is on the higher pressure system, and the lower hot water pressure just can not put enough pressure into the system to turn the switch off.
There isnt a leak, just an underpowered pump or over high set switch. 8)

Point of order. It's my system. There are two gatevalves as shown. The only ball valve is in the WC. Have you checked your PC for viruses ?

Thank you for the post. Already covered that in my OP. And the fix.

I'm more interested in an explanation of the latter part.

 

[sunnybob]

I see 3 lever ball valves on a manifold. A separate ball valve with a blue turn lever to the left, and a red handled gate valve to the right.
Are we looking at the same picture?

 

[owen]

What's it got to do with the OP's problem wether they are gate valves or ball valves? Absolutely nothing so you're just being petty.

 

[Eric The Viking]

I think your suspicion of the shower unit may be well founded. When reading what's below remember that our cold water pressure is mains (about 4 to 5 bar depending), and the DHW should be 3 bar, but often is higher because of the fault.

I have an ongoing fight with a shower in our place. It is apparently commonplace that the on/off /flow control comes AFTER the hot-cold thermostatic mixer part. This exposes the hot water side to the higher pressure, and naturally the two sides try to equalize. It's unusual to have DHW at a higher pressure than cold, so yours is probably doing in reverse what mine does. There are other freaky behaviours here - the main pressure reducer at the tank for the DHW hammers alarmingly (as there ends up with about 4.5 bar behind it, where there shouldn't be higher pressure). The cistern in the affected bathroom can fill with hot water rather than cold (hot gets forced into the cold system (flowing through the "off" shower mixer because the hot becomes pressurized slightly higher).

A good pressure reducer works, but don't fit double non-return valves as they make a ridiculous noise and don't seal very well. Singles might be better. We were doing OK until the cold pressure reducer in that bathroom failed. The other two (kitchen and downstairs shower) have been fine.

In case you are wondering, it's a tall house and I need the cold pressure to achieve a sensible pressure for both at the top of the house. The reducers stop backflow into the DHW side, or should, and allow mixer taps to work correctly.

 

[sunnybob]

1/ The first post was obviously humorous, as per the opening words and the smiley.
2/ The reply was not humorous.
3/ My response was to ask if we were looking at the same picture, how else can you diagnose from a picture if the wrong picture has accidentally been posted?
4/ regardless of the above, your post IS petty.

 

[Doug B]

As I said elsewhere I can’t believe the shower came without non-return valves as this prevents contamination of the mains cold water when the two waters mix which is a byelaw, though I appreciate you’re not on mains water Rog.
Basically it seems to me that your hot pump is trying to increase the pressure in you cold system when turning the shower off, non return valves will prevent this, I don’t really see why you were expect using the basin tap would do the same thing as the water generally mixes as the water exits the spout so they aren’t mixing in the valve. If they were mixing within the tap there would need to be non-return valves fitted under the tap, the taps I fit that do this come with non-return valves fitted as standard in the supply tails.

The ball valves Bob is referring to are known in my neck of the woods as lever operated isolation valves, not gate valves or ball valves :lol:

 

[RogerS]

As I said elsewhere I can’t believe the shower came without non-return valves as this prevents contamination of the mains cold water when the two waters mix which is a byelaw, though I appreciate you’re not on mains water Rog.
Basically it seems to me that your hot pump is trying to increase the pressure in you cold system when turning the shower off, non return valves will prevent this, I don’t really see why you were expect using the basin tap would do the same thing as the water generally mixes as the water exits the spout so they aren’t mixing in the valve. If they were mixing within the tap there would need to be non-return valves fitted under the tap, the taps I fit that do this come with non-return valves fitted as standard in the supply tails.

The ball valves Bob is referring to are known in my neck of the woods as lever operated isolation valves, not gate valves or ball valves :lol:

Doug...as ever, you've hit the nail on the head =D>

Digging through their literature they do indeed have such valves and say that if they malfunction then I'll get the problems I have. Will be checking them later.

 

[owen]

1/ The first post was obviously humorous, as per the opening words and the smiley.
2/ The reply was not humorous.
3/ My response was to ask if we were looking at the same picture, how else can you diagnose from a picture if the wrong picture has accidentally been posted?
4/ regardless of the above, your post IS petty.

1/ It wasn't funny.
2/ Because it was a pointless post by you in the first place.
3/ It's pretty obvious that the right picture had been posted you were just being petty about the terms.
4/ Thanks :lol:
5/Lets forget it now someone else has actually helped 8) :lol:

 

[RogerS]

As I said elsewhere I can’t believe the shower came without non-return valves as this prevents contamination of the mains cold water when the two waters mix which is a byelaw, though I appreciate you’re not on mains water Rog.
Basically it seems to me that your hot pump is trying to increase the pressure in you cold system when turning the shower off, non return valves will prevent this, I don’t really see why you were expect using the basin tap would do the same thing as the water generally mixes as the water exits the spout so they aren’t mixing in the valve. If they were mixing within the tap there would need to be non-return valves fitted under the tap, the taps I fit that do this come with non-return valves fitted as standard in the supply tails.

The ball valves Bob is referring to are known in my neck of the woods as lever operated isolation valves, not gate valves or ball valves :lol:

HansGrohe muppets. Just spoke to customer service who said that the backflow preventers are fitted at manufacturing time (although a replaceable item). Lookie lookie....none present.



Those wee black pistons are water hammer suppressors, I think. Nice touch.

 

[Doug B]

At least it’s an easy fix if quite annoying

 

[nolly47]

Hi
Looking at you plumbing system it’s a cold water tank in the loft with the hot water pump on the floor by the cylinder has the hot water pump got a none return valve fitted on the inlet side of the pump in the pipe work? If not fit one.
Steve

 

[RogerS]

Hi
Looking at you plumbing system it’s a cold water tank in the loft with the hot water pump on the floor by the cylinder has the hot water pump got a none return valve fitted on the inlet side of the pump in the pipe work? If not fit one.
Steve

No it doesn't have one. Do I need one ? I'm thinking about sitting the pump on a concrete slab to deaden the low frequency noise and so could do it then.

 

[Doug B]

Hi
Looking at you plumbing system it’s a cold water tank in the loft with the hot water pump on the floor by the cylinder has the hot water pump got a none return valve fitted on the inlet side of the pump in the pipe work? If not fit one.
Steve

I’d be wary of doing this Roger as the resistance caused by the non return valve could be enough to prevent the flow switch working on your hot water pump add to that that your cold pump is smaller with regard to output than you hot water pump I can’t see you having a problem.

 

[nolly47]

If you turn the cold-water isolating valve off to the on-suite bathroom then turn on the wash basin hot water tap so that the hot water pump runs then turn of the hot water basin tap what does the hot water pump do? What is the distance vertically from the shower rose to the underside of the cold-water tank in the loft? When you used the shower did it work as it should?
Steve

 

[RogerS]

If you turn the cold-water isolating valve off to the on-suite bathroom then turn on the wash basin hot water tap so that the hot water pump runs then turn of the hot water basin tap what does the hot water pump do?

Hi Steve, I'm afraid that I can't try that at the moment as the shower is dismantled pending arrival of their backflow preventers.

What is the distance vertically from the shower rose to the underside of the cold-water tank in the loft?

About 5ft. However, it's worth noting that the cold feed to all the taps etc in the house is fed via the 1Bar pump. That cold feed also goes to the coldwater tank in the loft which is used as the source of water to feed the H/W tank. It's historic. When we moved here, the cold feed was as per but the hot water was gravity fed. I could have removed the tank in the loft but I left it as a reserve source of water should we ever have a problem with the cold water pump (located in the cellar with the water treatment plant)

When you used the shower did it work as it should?
Steve

Yup...luxury...bluddy luxury

 

[nolly47]

Hi Roger
That explains a bit more you have a water treatment plant with break tank then a booster pump supplying all the cold water taps in the house from the cellar, there are no cold feed supplies from the storage tank in the loft except the cylinder supply. I assume that was installed before the on-suite bathroom. was the hot water pump fitted when the on-suite bathroom was installed? when you used the shower and switched it off did the pump run continually or was it very quickly stopping and starting.
Steve

 

[RogerS]

Hi Roger
That explains a bit more you have a water treatment plant with break tank then a booster pump supplying all the cold water taps in the house from the cellar, there are no cold feed supplies from the storage tank in the loft except the cylinder supply. I assume that was installed before the on-suite bathroom

Exactly so. When we moved here, only the cold water was pumped (because it had to be..from the cellar) but H/W was gravity fed and dribbled out. Pressure reducer in the cold feed in the really manky, grotty shower.

. was the hot water pump fitted when the on-suite bathroom was installed?

Before. House effectively re-plumbed. Bogs, 2 en-suites, bathroom, kitchen and utility. I counted up the outlets the other day...cold water - 15 ! So it was all zoned off with separate valves controlling each zone. As each zone came online, simply turn the valve on to test, then use.

when you used the shower and switched it off did the pump run continually or was it very quickly stopping and starting.
Steve

Both. Discovered it depended on the setting of the temperature control on the shower which then led me to discovering that the backflow preventers had never been fitted by Hans Grohe at manufacture time. Still waiting for them to arrive.

 

[Eric The Viking]

It's infuriating - I share your frustration.

We get all these silly water regulations about non-return valves all over the place*, but there seem to be no constraints on the badly-designed rubbish sold by both the sheds and the up-market kitchen and bathroom boutiques.

What you pay for plumbing fittings (taps, faucets and other visible stuff) doesn't bear much relationship to quality, a lot of the time. Our present kitchen mixer tap was the cheapest so far (third in that sink!), and has lasted the longest by far. It's also been the easiest to find ceramic cartridges for.

Given their prices, Hans Grohe ought to be giving you far better service, BTW. We 'inherited' a big showerhead of theirs with the house, which I've kept in service. It's a lovely shower, but I was shocked to find it was last on sale at 350 quid (just the showerhead!).

Hope it's sorted soon, E.

*I have had to remove them from outside taps, in order to stop my jetwash from being damaged by poor water flow.