Plumbing Question - Shower not hot

[brianmoooore]

Essex flange is just a threaded boss with no internal 'works' . Can be used for a shower if fitted on the dome of the cylinder, but presents venting problems unless the pipework from it rises.

 

[brianmoooore]

Knob position needs to be sorted ASAP, then. That's why I said to mark the original position of the shaft.
Stored water temp. should be near enough the same whether heated by the immersion heater or the boiler. There's a thermostat under the cover of the immersion heater (electricity OFF), which may be marked in degrees, although they haven't been calibrated for many years. If it's an uncalibrated one it left the factory with the dial locked in place by a blob of sealant. Check for it having been 'got at', or it could just have gone wrong of course. if it has a calibrated dial, it should be set at 65 degrees.
The hot water temp, if the water is heated by the boiler, is set by the thermostat that can be seen strapped to the front of the cylinder. This should be set to 65 degrees as well. Can just make out the knob position in the pic, and it doesn't look far out.
The boiler flow temp. must be set slightly higher than the 'stat on the cylinder, otherwise the boiler will cycle on and off after the cylinder is 'full'. I suspect many boilers now suffer from this problem, following the misinformation put out by the government green brigade.

 

[Mark Wright]

So what are you thinking the Sussex flange is malfunctioning?

 

[brianmoooore]

Not much to go wrong with them, other than build up of scale.
First priority is to work out why there's a big difference in hot water temperature between that heated by the immersion and that heated by the boiler.
It would be interesting to disconnect the feed to the hot water side (at the front in the pic.) and see if you get a decent flow there.
Check than 'in' and 'out' are the right way around on the pump. Ignore that. I can see they are correct in one of the pics.

 

[Mark Wright]

Still so puzzled -
The tap gets hot
The shower doesn't
The hot water from the Shower goes through the pump
But both come from the same source
The flexible cables entering the pump aren't hot but warm
With the immersion heater on the shower gets hot.

But I think they did replace the pump and do some work on the S plan when the boiler was replaced - and I had a feeling this all happened when the boiler was replaced. I think they should come and fix it for her but they've already told here it was the shower and she had a new shower fitted on there advice.

 

[mainline]

I’ll refer to my post #4

It could be that with the higher water temperature, the Shower thermostat valve is opening.

When the valve isn't allowing a hot flow, your in and out of the pump is going to be cooler as there is little flowing though it.

 

[Mark Wright]

I mean I know nothing about this really but I can't understand why it's not entering the pump hot but the tap is ok. Anything I can try?

 

[Mark Wright]

I think ill leave it tonight. I've turned the thermostat at the front of the tank up to 65 it was at about 59.
I'll go back tomorrow and have a look - maybe one last go - and maybe I'll advise here to get them out to fix it.
But thanks again I really feel like this has helped and if they do come back I can mention the pump etc. I'm not looking forward to it I know there be all defensive etc.

 

[plugsandsparks]

Must admit, i am getting confused myself following this but do hope you get it sorted. At the moment i cannot fathom whether the pump runs both for hot water at the tap and shower.
1. Try run hot tap until water is hot, check temp at pump is it the same temp
2. Shut off hot tap and run shower until it is at its hottest, is the temp at the pump the same as the shower or same as when you ran the tap.

Reason i am confused is that there is talk of the shower take off from the cylinder being lower than the top take off and there is talk of the pump running when either tap or shower are running.

 

[Mark Wright]

I know, is confusing now 9 pages

But the pump is only used when the shower is on - So this has ruled out other things such as pressure issues.

Also the Shower only gets proper hot with the immersion heater element switched on.

 

[brianmoooore]

Reason i am confused is that there is talk of the shower take off from the cylinder being lower than the top take off and there is talk of the pump running when either tap or shower are running.

There's a Suffolk flange fitted, so the shower hot water comes from about three inches lower down the cylinder than the rest of the hot water. This shouldn't make any difference to comparative water temperatures until the hot water is nearly all used up.
It would be very unusual to feed downstairs taps from the same pump that feeds the shower, but not impossible.

 

[plugsandsparks]

OK so maybe impeller has fell off, could try turning pump off and running shower to see if it is exactly the same?

 

[mainline]

I wonder how the OP is getting on.
It's always nice to have an update on the outcome.

 

[Mark Wright]

I wonder how the OP is getting on.
It's always nice to have an update on the outcome.

I hate that when they just disappear
Sorry, as you know I turned the thermostat up on the tank and yes it is warmer but it's not right and I do feel this has led me in the right direction because I did feel it wasn't right from when the boiler was changed.


I would like to get a thermometer suitable to measure the temp if anyone could recommend one?

Another thing if I quickly turn the temp right down and right up it is hot for like a second.

Also this has made me what to learn S and Y plan etc I've been putting it off - I'll probably start another thread at some point.

But I'll say it again this is a great forum with some really helpful people.
Mark.

 

[Mike Johnson]

I think the problem may be the shower mixing valve is designed for mains pressure and the OP has only tank gravity pressure, or the pump may be caput and will not operate correctly with the pressure now available with the new boiler, which again may be designed for mains pressure and only has gravity pressure, both need checking, whatever is causing the problem seems to be a disparity between the boiler, shower pump and tank pressure differentials.

The lack of gravity pressure equipment is a continuing problem for older house's and installations.

 

[brianmoooore]

I think the problem may be the shower mixing valve is designed for mains pressure and the OP has only tank gravity pressure, or the pump may be caput and will not operate correctly with the pressure now available with the new boiler, which again may be designed for mains pressure and only has gravity pressure, both need checking, whatever is causing the problem seems to be a disparity between the boiler, shower pump and tank pressure differentials.

The lack of gravity pressure equipment is a continuing problem for older house's and installations.

The shower valve in question is designed for a minimum pressure of 0.4 bar.
It is fed from a purpose designed shower pump which should be capable of providing a pressure of 1.5 bar - 3.0 bar, depending on the exact model, so it should work properly.
The design and layout of all the plumbing we can see in the pics is OK, although a little odd in places.
There's something that has failed, is not set up properly, or is partially blocked.
I'm still unclear if the shower worked properly when the water was heated by electricity, or was just 'better'.

 

[Mike Johnson]

Ten pages of going around in circles eventually we will disappear up the shower head, seems to stem from the replacement of the shower mixer and boiler at the same time?

 

[LukeD]

This is so simple..... get the temp of the hot water tested as close before the mixer as possible . If its as hot as expected .Buy a new mixer ..... !

 

[Mark Wright]

This is so simple..... get the temp of the hot water tested as close before the mixer as possible . If its as hot as expected .Buy a new mixer ..... !

It's a brand new shower.

 

[Mark Wright]

Anyway like I said I feel I've been put on the right track - for some reason the water entering the pump isn't very hot, unless I use the Immersion. I think I'll measure the temp(i.need a thermometer) and just go to the company that fitted and say look this is the temp here's what I found, fix it.