Pulsing Overly Hot Shower

Hi Folks,

I moved into a place recently where the shower was off/not-working and the landlord promised to fix it.

After fixing it (or turning it on), the only operation we can get from it is for it to put out very very hot water, at a very low pressure. This is with the temperature turned all the way to the hottest (9). If we try to turn the temperature down to a cooler temperature, then it causes it to run in bursts - 1 second water on, 1 second water off.

These are the things I know about the system:
-It looks like an electric shower on the wall - it has an on button, a temperature dial and another dial that makes the motor sound louder or softer but doesn't do anything for the operation of the shower
-Even though it looks electric - it takes water from the hot water tank in the cupboard - so it is somehow mixing this with cold water. I know this because it is cold when the water is out.
-Sometimes, very rarely, we can turn it on and find fantastic pressure, and with good pressure we can adjust the temperature. I have no idea why but it tends to be in the middle of the afternoon that this can happen.
-We have the boiler timed to heat twice a day, once in the morning once at night
-We have tested the system with no hot water in boiler tank (ie cold), and also with a full tank, also while the boiler is heating and while the boiler is off - but it makes no difference.
-The boiler is on the same level - it is a single story ground floor flat.

Does anyone know about pulsating hot showers like this and how to fix it? Or what to replace it with?
My landlord says that his "handyman" has had a look and there is nothing that can be done because the plumbing is 50 years old. I think he is lying and just doesn't want to pay to put another shower unit in - surely some sort of "working" shower installation must be possible?

Would running a proper electric shower that heats cold water on the fly alleviate the problem do you think?

I am desperate to get the landlord to do anything, my girlfriend is used to 2-3 showers per day and is going crazy, and we have been showering with a bucket for the past month
It's a hassle to move house all over again just for the shower, and then the next tenants will have the same problem so there must be a way to fix shower problems.

Thanks for any advice,

Dan

Could be that the water coming out of the HW cylinder is too hot. If it's Over about 63 you can get "cavitation" in the pump (low pressure, so water boils at it would up a mountain..) so the water stops and starts while it tries to pump vapour.
Maybe in the middle of the pm your HW has cooled down a bit.
Solution would be to turn down the thermostat which is in the immersion heater head (assuming that's how you heat your HW). That assumes the stat actually works - the old ones failed "high" which was dangerous.
A new thermostat costs a few quid and takes minutes to fit.

To see the stat, turn off leccy, undo the single nut/screw on top of the immersion htr head and you'll see it. triangularish, two wires and a temp scale, all floppy like.

Before going further check if the inlet pipes to the booster pump are the correct way around . Thermotsats can jump if piped up in reverse,

Our system heats in a boiler in the kitchen, which then puts it into a water tank in a storage cupboard between the kitchen and the bathroom.

I looked around and there was a dial with numbers on it in the cupboard near the tank. It was set to just over 63 - so I assumed that was temperature celcius and it is the thermostat I guess.

I changed it down to 45 for the purposes of testing. Then I opened the taps and used out all the hot water.
Turned the boiler on again and heated it up.

Tried the shower and tada it works with decent pressure!! A little cold though, so adjusted the thermostat to 50degrees. Still experimenting for the perfect temperature to pressure ratio but it's looking good. And to think my landlord reckons there was nothing that could be done I can't believe it.

I think the problem started when the people came to do the "gas safety certificate", I was only in there 1 day and they did that and the shower was like that. Maybe during "gas safety" they have to set or test the thermostat or something.

Thanks you're a legend Chris!

Cheers

Dan

I have a similar problem with a gravity feed shower. I had the central heating boiler temparature up quite high by mistake, and the shower pulsated a bit with the hot water. There was plenty of cold water as well. I also have some leakage from the hot water storage cylinder. Could this have been caused by excessive cylinder temperature? Is there a safety pressure escape? I would need to strip all the insulation off to verify where the leak is coming from, and I don't want to do that yet.

The cylinder has an immerser heater for backup which is never used, and this has a thermostat, but how do you control the temperature of the hot water when it is heated by the central heating system?