Hot water tank help please

ukjoel

Our shower term is either too hot or cold.
Its a mains power shower heated by traditional boiler and a hot water tank.

I have been trying to eliminate issues to narrow down the problem.
The timer is about a year old and comes on when it should (downstairs) and lights up.

The boiler then does nothing with water temp set at 40.
When I move water temp (on hot water tank) to 50 the boiler reacts and light comes on and water heats up but is too hot.

However shower is also then very very hot. If I turn shower temp (on shower)to below 30 it just stops and any higher than that its too hot.

I suspect that the pump (which is about 7 years old) and is noisy and seems to stop start a lot is struggling to add cold water. I believe the feed in is mains plus tank (there are three feeds).

This combined with a very old and basic thermostat on the tank means water is scalding or freezing.

Apologies for the long post but wanted to post all the relevant info.
Boiler is a Worcester 19/24 CBI that's again about 7 years old and been fully serviced and has worked well.

The shower pump is a Techflow QT45
The water heater thermostat is a Honeywell L641A1039
The immersion (is on a auto timer to turn off after 15/30/60 mins) and is hardly ever used.
All worked fine until last week although pump has always sounded ill since we moved in (but not sure as not had a healthy model to compare it to.)

My thinking is to change the pump and thermostat at the same time but wondered if I maybe missing something obvious (or maybe not so obvious)

Many thanks in advance.

Myser

If you want a constant fixed temperature of water when showering, you should install a thermostatic shower.

Is the tank thermostat securely attached to the tank?

Do you have a thermometer/thermocouple that you can use to compare the temperature set with the actual temperature?

Stuart Turner pumps are very good and before swapping it out, check whether it is still covered under the warranty.

southcoastrgi

why do you even have the immersion switched on ? timed or not, sounds like a knackered cylinder stat or as above it's not correctly fixed to the cylinder & not in contact with the cylinder

ukjoel

Thanks,

I believe the shower is thermostatic. Temp is marked in measurements on it (a Grohe shower) rather than hotter and colder. I cant see any model number or name so cant be 100% sure. When we turn it to reduce the temp (below 30) it stops. 30 plus its very hot water.

This is what makes me suspect the pump. I dont think its pumping enough cold water in with the hot. The shower reacts by stopping when we ask for cold water. It wont give us a cold water shower (unless the water tank is set to 40 - a reading it considers to be 'off')

Tank thermostat is attached well and doesn't appear loose. The dial turns freely although doesn't seem to have much flex between 40 and 50 with 40 giving us room temp water, and 50 giving us far too hot water (think it ranges from 40 - 90_. From memory its always been set to 50 previously without their being an issue.

Thanks for warranty tip but I think its well outside the 2-3 year warranty on them.

The shower is used twice a day (often more) so possible pump has reached its life. I suspect tank thermostat is working but not particularly sensitive.

The immersion is not switched on. We replaced the standard on/off switch with a push button countdown timer that ensures if turned on will switch itself off after 1 hour. This eliminates the chance it may be left on by mistake.

Cheers

ukjoel

Cheers SCC,

I have checked the cylinder stat contact and its nice and tight against the cylinder with no give or wriggle room.

I have ordered a replacement cylinder stat as they are not too expensive and agree its the best first move. Funnily enough its the same model as the one we have but it looks like that one has been produced for a good few years.

If that doesn't work then will come back for a plan B.

Cheers,

cyclonebri1

Just a thought, where abouts is the stat clamped around the cylinder?

If it's too low then that could be your problem, the water feeds from the top and there can be a vast temp difference from top to bottom.;);)

ukjoel

Its positioned about a third of the way up (maybe a tad higher) but seems to be in the correct position according to what I have picked up online.

Its also been in the same spot for at least the last couple of years (and probably 7 years plus) and worked ok from there.

This mornings shower temp was good and my suspicions are that the stat (while working) is not sensitive enough so have ordered a replacement. I think the reason the got the right temp this morning was that by playing with it to check it I have inadvertently found the right temp zone between room temp 40 and much too hot 50.

I have also fitted a second strap around it to ensure it firmly against boiler (although none of my previous checks indicated it was loose or not tight to boiler).

Will monitor it over next few days (without touching the stat) and see what happens.

Thanks for all the help.

cyclonebri1

ukjoel wrote: »

Its positioned about a third of the way up (maybe a tad higher) but seems to be in the correct position according to what I have picked up online.

Its also been in the same spot for at least the last couple of years (and probably 7 years plus) and worked ok from there.

This mornings shower temp was good and my suspicions are that the stat (while working) is not sensitive enough so have ordered a replacement. I think the reason the got the right temp this morning was that by playing with it to check it I have inadvertently found the right temp zone between room temp 40 and much too hot 50.

I have also fitted a second strap around it to ensure it firmly against boiler (although none of my previous checks indicated it was loose or not tight to boiler).

Will monitor it over next few days (without touching the stat) and see what happens.

Thanks for all the help.

Move it higher, if no better replace then chap, ;)

plumb1_2

As you cant get cold water to the valve, check the filters on the shower valve, and flush out the pipe work to check operation of pump.

keystone

HW cylinder should be at 60 degrees. 1/3 way up is correct position for Tankstat.

As plumb said - check filters in valve.

I suspect that the pump (which is about 7 years old) and is noisy and seems to stop start a lot is struggling to add cold water. I believe the feed in is mains plus tank (there are three feeds).

What does this mean? Stop / start might mean air in pump or air in cold feed to pump. Cold feed to pump should be by direct and independent pipwork from CWST NOT mains.

Cheers

cyclonebri1

keystone wrote: »

HW cylinder should be at 60 degrees. 1/3 way up is correct position for Tankstat.

As plumb said - check filters in valve.

What does this mean? Stop / start might mean air in pump or air in cold feed to pump. Cold feed to pump should be by direct and independent pipwork from CWST NOT mains.

Cheers

|You must charge too much, that's far too long a holiday.;);)