Low Hot water pressure

[AndyJ]

Hi guys - experiencing a multitude of problems at the moment. Appologies if this is too long and I'll excuse those that can't be bothered to read it all.

About 18 months ago we had a Thermostatic Power Shower fitted and a 2bar pump. There was no shower before. Pump was installed by a plumber - taking cold from the attic - and hot water from the cylinder (obviously). Everything fine for 12 months.

After 12 months and one day - the pump developed a leak on the hot side of the pump. After arguing with the pump vendor and retail outlet - I bought a Salamander 1.5bar pump, and fitted.

However - since then - things having not been going right.

[1] Hot water pressure downstairs is getting lower as time goes on. At the moment - its taking 20 seconds to get 1Litre of water out of the tap.
[2] The shower is "pulsing", varying the speed of the water coming out of the head, and also the temperature. This only happens when you demand a certain temp of water (ie, all hot - OK, all cold OK, in the middle, not ok).

[1] suggests a blockage - as it got worse and was not an immeadiate change, but one over time. Reasonable?

[2] I'm stumped on -as the only thing I changed was the pump (was easy - or so I thought! lol). Any clues?

Maybe the two are related?

Look forward to you replies, and a nice warm shower again

 

[seco services]

hows the hot pipe connected to the cylinder.
sounds like you may have an airlock if your loosing pressure to downstairs taps aswell.

try bleeding the pipework.

 

[TicklyT]

A restriction in the cold feed to the bottom of the hot cylinder could lead to the pump drawing air down the cylinder vent.

That could result in airlocks in the both the pumped and unpumped hot outlets.

The flow to hot taps may fail because of airlocks, the pump performance would become erratic, and entrained air in the water could damage the pump.

At the top of my list of 'usual suspects' would be a 'foreign body' in the cold storage tank blocking the outlet, then any gate valve in the cold feed to the hot cylinder. It's not unknown for the internals to fail, so the valve can't be fully opened.

 

[AndyJ]

Thanks chaps.
At the affected tap is a mixer tap, I tried the method of holding the outlet of the tap, turning on hot, then cold for 30 seconds - made no difference. Tried this about 3 or 4 times.

Then I attached the mains fed cold inlet to the washing to the hot inlet - I could feel the water gushing through the pipe. Turning on the hot water tap the water was now cold - testament to the fact that cold water was being forced into the tank I presume ? Water went cold after about 2 or 3 attempts at this method.

One thing I struggled with understanding - if there is an airlock in the system - where does "back flushing" send the air too? Or am I misunderstanding

Pressure still low at the tap - so one assumes this rules out an airlock - and is therefore something more physical? (limescale?)