VOKERA LINEA 24 RUNNING HOT COLD DURING SHOWERING

[retch29]

I have recently moved into a new flat and the boiler is a Vokera Linea 24, when I run the shower after a few minutes the water pressure starts fluctuating then the water temperature drops to cold before slowly coming back up to the desired temperature and repeats this cycle over and over.

The hot water to the taps sems to run fine and the central heating runs fine also.

The shower is a crosswater kusasi 1000RC the water supply for this seems to come from a pump in a storage cupboard - as far as I can tell.

What can be the problem with the shower temperature?

My plumbing skills aint to good so I'll get someone to have a look at it but would like to get my head round the problem before getting someone in.

Also does anyone have a manual for this model? Can't find one on the Vokera website.

 

[gas4you]

A shower pump must not/cannot be used on a combi installation. Combis can only give the water they want to give. If this is a pumped shower then change to normal shower

 

[retch29]

I'll give you more information:

Boiler Vokera Linea 24 - as per identity plate.
Shower in ensuite - Triton T80 SI
Shower in Bathroom - Crosswater thermostatic Kusasi 1000RC operates minium 0.1bar pressure.
Shower Pump Watermill BP100S

When you start either the ensuite or the main batthroom shower the shower pump starts running.

The original setup in the flat was with the T80SI only. The T80SI works ok on it's own, no apparent problems with the temperature.

 

[retch29]

Further update:

The pump starts up whenever a water outlet is opened.

I have subsequently switched off this pump.

The result being that the thermostatic bathroom shower seems to be running ok, no recurrence of previous symptoms.
However the Triton shower now has a low pressure indication whilst running.

It seems the Triton is happy to run with the pump but the crosswater thermostatic is not.

Is there any possible solution to getting both working ok?

 

[locosaki1978]

This is just guess work,as I have not seen the set up.I assume your Triton is an electric shower,If so it could possibly be connected to a tank feed rather than mains pressure,hence the reason when you turn pump off water pressure light comes on !!
Now if you have a combi boiler the previous post about the pump is spot on.You cannot run a pumped shower through a combi boiler.Get a little more info and get back to me!!

 

[retch29]

The flat is new build and is 1st floor there is no water tank that I am able to find.

The Triton is an electric pumped shower from the info I can find.

The watermill pump has a single inlet single outlet.

Setup in hall cupboard.

There is a mains stop valve, the inlet and outlet pipework both run under the floor.

There are 2 shut off valves on apporx 24mm pipework, the first one shuts off the cold water to the various users.
The second one, applying some creative licence here, is on the outlet to the water pump. Thus the "hot" water comes from the combi boiler to the pump via this valve, the pressure is then boosted and fed to the various users. If the valve is not on the outlet it's on the inlet but this would mean you could run the pump dry and knacker it very easily.

Water pressure throughout the house is not particualrly high.

Cheers for the ongoing help folks.

 

[DP]

Reading in between the lines, I would suggest the pump is fitted to boost the cold water only. The Triton is a bog standard 8 kw electric shower.

Triton relies on mains pressure being adequate before it will power up, hence LP light comes on when the booster is switched off.

Meanwhile the boiler is happy to work to low pressure (as indicated- 0.1 bar)

Two areas I would be investigating would be 1) pressure differential between hot and cold when pump is running and 2) possible sedimentation/ muck in the primary water in the heating system.

 

[gas4you]

I am guessing that the problem is a pressure imbalance. If the combi is runing at lowest pressure on cold to hot but the cold to the shower is pumped then this will cause the hot/cold problems originally said of in thermostatic mixer shower.

I had a similar problem I was called into where it turned out someone had replced an unvented cylinder with a standard gravity cylinder as they were moving and the new owner was left with the problem.

I am suspecting that the only possible thing here is that the pump is supposed to be on the cold mains inlet in the property and is supposed to boost water all to cold taps, even cold supply to combi. Haven't heard of this before but in theory could work. Check pipe work off pump is correct

 

[ChrisR]

All guessing a bit here...

The pump pumps cold water, right? (Feel the pipes)
If it has any valves on it, shut one and see exactly what stops.

It seems it's pumping cold to the Triton but we don't know if that's from the main (improbable) or a tank somewhere (like in the top of a cupboard).

How good is the cold mains pressure at the kitchen tap?

 

[retch29]

Hi Guys,

the pump is actually pumping cold water as you correctly suggest, so can I assume that there is a cold water mains supply to the pump and the pump is boosting the pressure of the cold water prior to it entering the boiler?

Shutting off the stop valve associated with the pump stops water coming out of the hot taps.

Shutting off the 2nd stop valve I've mentioned shuts off water to the cold taps.

Could it be that because the output pressure of the shower is very low and it is thermostatically controlled that this is causing the boiler to cut in / cut out and subsequently cause the pump to do likewise?