Pump fed shower 'running out' of hot

KaneToad

TLdR: Pump fed shower "running out" of hot water while system still has plenty of hot water in it.

Tried writing this before...but lost it all, apologies if it double posts.

Elderly mother in law has issue with hot water to her pump fed shower.

The shower is fed by pipe from hot water cylinder but this is only Luke warm while other pipes from cylinder are very hot to touch.

Any suggestions on anything I could try to fix this problem for her? All suggestions appreciated.

Pipe 1, is the issue. It comes out of top of cylinder and T junctions - it goes up into attic (or comes down from attic, depending on interpretation!). On its downward journey from the T junction, it branches off again and leads to the shower pump. If I place my hand on pipe above red tap just before braided connection to shower pump, it is only lukewarm. I would expect this to be very hot as it is the hot feed for the shower pump, no?

Pipe 2: comes out of middle of cylinder. Connects to expansion vessel above. Pipe is very hot to touch but reduces heat as it turns to go up to expansion vessel (not in pic). Pipe 2 also travels down through floor and links in with motorised valves. There are two motorised valves. They control flow of water to rads in two zones. Upstairs and downstairs. When both motorised valves are closed, only hot water for taps is heated.

Pipe 3: is at bottom of cylinder. It is not hot to touch. It enters cylinder from attic (or exits cylinder to attic!).

Pipe 4: is at bottom of cylinder. It is very hot to touch. It heads off downstairs through floor, (or comes up from downstairs!)

When the power showers (pump fed) are run, the hot water doesn't last as long. Yet when the separate bath (not pump fed) is run the hot water seems hotter.

It's puzzling me that although there is plenty of hotwater in the cylinder, the power shower (pump fed) seems to run out of hot water. Is it possible that there is an airlock in pump end of things?? If so, how would this be easily rectified?

TLdR: Pump fed shower "running out" of hot water while system still has plenty of hot water in it.

Lenar3556

The first thing to establish is if the full volume of water in the cylinder is getting up to temperature. What is heating it? Is there a zone and thermostat specifically for the hot water? Is there also an electric immersion heater?

Pipe 1 is hot water leaving the cylinder going to taps/showers etc.

Pipe 3 is cold water feeding the cylinder from the attic tank.

The other pipes all look to be central heating, but we can’t see exactly where they are going. Pipe 2 is likely a flow from the boiler to the heating coil within the cylinder used to heat the cylinder from the boiler. More photos would help.

The most likely explanation here is that the cylinder isn’t being heated fully.

When you turn on the hot tap on the bath, how hot is the water? It should be close to 60 degrees to prevent legionella growth - like very hot, steam coming from running tap etc.

How long does the pumped shower run before it goes cold?

John.G

Switch off the pump, shut the red gate valve before the braided HW hose to the pump, then open but do not remove the hose where it connects to the pump, when/if no more water issues, remove the hose, put its end into a bucket and open the gate valve fully to establish a good flow until bucket nearly full, is it very hot?. If so possible blocked strainer on pump (HW) inlet, clean it and also the cold one.

You may have a problem with the shower thermostatic mixing valve.