Shower has gone cold!

Rosanante1

Long story short:

We have a boiler and cylinder for hot water and central heating. Big cold water tank in the loft and mixer shower feeding off independant hot and cold water pipes up from the cylinder across the loft floor and down into the shower.

Has been working fine for many years. But recently started to have a very slow flow of hot water. To get a decent temperature to shower in is almost impossible at the moment.

When set at coldest on mixer unit, water flows strong and cold. When set at hottest on mixer unit slows to a trickle. HOWEVER.... when I put the shower head on the floor of the cubicle it flows hot and strong. Basically, the higher I lift the shower rose, the slower the hot water comes out.

Now I know what you're going to say: lift the cold water tank, blah, blah. But the thing is. this has only happened recently. It happened last week but seemed to solve itself when i just ran the shower hot and on the floor of the cubicle.

There is only one common denominator, it has happened 3 times now and only after my daughter used the shower. Yes she does take ages in there and yes she runs it until all the hot water is gone. Coincidence? :think:

Still struggling this morning. Any ideas?

ormus

does it work ok first thing in the morning when all the tanks/cyls are full?
how high is the cylinder in relation to the shower rose normal height?

you should have a 1m head, in both hot and cold pipes.

the CWS tank in the loft should be ok.

ps
if you use all the hot water, itll take time to reheat some more water. the HW cylinder is basically just a storage vessel.

Rosanante1

ormus wrote: »

does it work ok first thing in the morning when all the tanks/cyls are full?
how high is the cylinder in relation to the shower rose normal height?

you should have a 1m head, in both hot and cold pipes.

the CWS tank in the loft should be ok.

ps
if you use all the hot water, itll take time to reheat some more water. the HW cylinder is basically just a storage vessel.

Thanks for the quick reply.

The HW cylinder is in a small cupboard next to the bathroom. The rose at showering height is about half a metre higher than the top of the cylinder. The CWS tank in the loft is about 1 metre above the height of the rose. As i say, it has been working fine for many years.

It has plenty of hot water and i still had the problem even after leaving the immersion on for a couple of hours. (Normally the boiler heats the water). I checked other sinks and the water is piping hot there.

Ros

absent_dad

This can be cause by several problems.

The more likely cause is a stuck thermostat control, usually cream crackered, you can replace but if you have an old unit the parts may be difficult to come by so a new mixer needed, most home diy stores supply a range.

Your hot water pipe could be blocking, do you live in a hard water area which could lead to 'furring' of the pipes so restricting the flow/pressure. Also there may be a sticking washer inside which also gets coated preventing the hot opening.

If your hot water is 'too hot' then this can also close the thermo down so only letting cold water through, maybe in need of a flow resistor.

Prob going to need a plumber take a look.

Hope this helps

Rosanante1

OK so far with the advice.

Just to reiterate, when the rose is placed on the floor of the cubicle, the hot water flow is strong. The higher I lift it, the slower the flow becomes. This has happened about 3 times in 6 weeks, then goes ok again.

Air in system? Water pressure fluctuating?

ormus

poss the cold supply pipe partially blocked so only filling the cyl very slowly.
or same with the CWS tank inlet valve.

or maybe it is the mixer valve. a strip down and clean does wonders sometimes.
you can buy service kits for the brand name ones like Mira etc...

Wookey

Several other possibilities here, partial airlock in the pipework leading to the shower or the inlet filters on the shower body may have dirt lodged in them. If its a mira shower it will need to have the water supply turned of and the body removed from the shower housing, once out look for the filters in both inlets, remove these and clean if needed. Also to ensure a full and adequate flow out from both inlets turn both supplies back on with the shower body still out, (only do this if there is no danger of flooding the place) check and see if water flow from both inlets is the same, dirt or any air within should be shifted once the full bore of the pipe is left open like this.

Rosanante1

Looks like i'm gonna have to take a day off and try a couple of these suggestions, so keep them coming!

I fitted the shower mixer unit myself about three years ago and was really nervous because i'm an amateur. The two pipes lead down from the loft behind the drywall and the tiles. The old unit was very flimsy in its fixings and i made sure the new unit was secure and not weeping (my worst nightmare) behind the wall.

I really don't want to take the unit off the incoming pipes again unless all other suggestions fail.

Wookey

What make of shower fitting is it? Most makes don't need removing, they are usually able to be taken apart from the front for servicing.

st999

I would check and see if the tank in the attic is perhaps getting emptied because the shower is using the water quicker than it is getting refilled because of the length of your daughter's shower.That would let air in which could cause your problem

Stan

Rosanante1

Quite bizarrely, I've had two showers since I last wrote and the shower is back to normal. It could have been an air lock or fluctuating incoming pressure.

Anyhow, I have fully opened my incoming mains stopcock which I don't like to do because it tends to make my cistern ball valves drip and subsequent run-offs from the overflow pipes, but I have changed all but one now. Perhaps that will increase the flow into the HWT/CWT and prevent a recurrence.

I ought to check the valve for blockages. My unit is a Trevi Blend Exposed Shower Valve. I might see if it can be dismantled from the front.

Thanks so far,

Ros