3 port valve & very hot shower.

[novice29]

A few days ago our power shower stopped working, probably due to the anti-scalding cut-out. I traced the problem to the 3 port valve (Danfoss 28mm) which does not shut off hot water to the hot water tank when rads are on only. So hot water is heated when rads are on! Also noticed that cold water feed to shower pump is getting hot when shower is off, so it seems the pump is mixing hot and cold feeds. I suspect the very hot water feed has damaged a seal within the pump (Jetforce 75). I have managed to shutdown hot feed to cylinder and to header tank by manual valves, so water is kept at safe temperature & header tank not heated up.
Any idea if pump can be repaired?
Thanks.

 

[novice29]

OK, I realise the initial question was a bit unusual for the experts out there. After speaking to the shower pump manufacturer, they suggested that a graphite washer may be the problem (certainly cheaper than replacing the whole pump!). The part is ordered and should be "in the post" today.
Has anyone else done this on their shower pump? Any special tools required (apart from a big hammer)?

 

[novice29]

Just in case anyone follows this tale. I have relaced the 3 port valve and graphite washer in the shower pump, and now have hot showers once again. The "paddle" inside the valve was not closing off the hot-water completely, and looking closely at the paddle, it is slightly deformed.

The old graphite washer inside the shower pump was completely smashed to zillions of pieces! Most of these had to be cleaned out of the pump, and also out of the shower mixer when water was reconnected. We also noticed how much quiet the shower pump is now!!

Total parts cost about £60.

 

[ChrisR]

INteresting tale. Why dyuo think the graphite washer dsintegrated?

 

[novice29]

I'm not 100% sure. We have a salt water softener installed on the cold water input into the house. I wasn't too good at chemistry, is it possible that salt water + graphite don't mix too well?

I tried searching the web for manufacturers of graphite bearings, it seems it is a common solution for bearings which cannot be lubricate (with oil or grease). But no information on possible side effects.

Maybe we'll just get used to replacing the pump bearing every 3 years or so. I wouldn't mind but there is not much space in our airing cupboard!