Pump not working correctly

[electrospark]

Hi
I'm having an issue with a water pump which pumps my hot water supply from the hot water cylinder.
The system I have is a mains fed cold water tank which feeds a hot water cylinder which is heated via a communal boiler. The pump I have is a vari speed si50. It's connected to the hot water supply immediately after the hot cylinder.
The hot water feeds the bath, bathroom sink and a kitchen sink all within 10meter from the pump.

So the problem, you turn on the hot water tap and the water trickles out the tap as if the pump wasn't even there. It will kick in after a few seconds or on a bad day not at all. I find if you tap the pump with the tap open this will start it.
To me it sounds like there isn't enough flow to bring on the flow switch. The thing is I changed the pump around 1 year back when the old one died. The old pump also had the same issue before it gave up. The new pump worked better but I wouldn't say it wasnt 100% by any means.

Any ideas?

Thanks

 

[blackfriars]

hi , is it the same problem with all the hot taps connected to the pump
do you have a separate feed for the pump this is a single impeller pump, only to be used with 1 tap at a time
have you checked to see if the filters in the flexi hoses are blocked
it could be the flow switch , but i would check filters first
these pumps should last you more than 1 year
have you checked what speed the boost dial is set to

 

[electrospark]

Yes it's the same with all the taps. The bath tap is the worst as it doesn't turn on fully as my tenants have let a little too much lime scale build up on it. I'm going to replace the block on the bath so this isn't really an issue.

I tried increasing the speed on the pump but this doesn't seem to change anything because it still needs the initial flow to trigger it.

The filters could be a good place to start. I will check them although I don't recall any build up in them last time.

It's coming back to me that I recall the pump having 22mm hoses when I fitted it and I had to get 15mm ones as the incomer is only 15mm. Could the supply pipe be too small? All off the pipe work is 15mm... 😕

 

[blackfriars]

hi, your pump is able to operate with either 15 or 22mm
as for the bath tap just change the ferrel
if it is less than 1 year old your warranty will cover , if you registered it upon buying it you will have a warranty for 2 years , just for parts , not labour
if you have no success with cleaning the filters you could look at getting 1 of these pumps , a techflow tp-55 rated at 2 bar much cheaper than the si-50 comes with a 2 year parts and labour guarantee