Scala 2 pump cycling every 15 mins

FGR · 11-06-2024 11:39pm #1

Hi all.

I'm being driven demented here. Have a 6 year old house with a system that's pumped by a scala 2 pump. Its an urban setup so the house is mains provided with good pressure but plumber suggested it as I have two rainfall showers.

The pump was replaced under warranty in 2021 after it decided to leak all over the place. Plumber took it and replaced it under warranty. The new one was fine until recent weeks whereby it cycles on and off for about 6 seconds every 15 mins or so. I checked the showers, toilets, sinks etc for a leak including turning off valves to them but it seems to still do it.

Plumber then came and checked house and said it's ok that it's normal for the pump to cycle as houses get older and suggested turning off the pump at night. That can't be right can it ?

I'm at my wit's end here. I figured out how to turn off the pump and use the normal supply in the meantime but am worried now there's some hidden leak under the floor or between the walls that could come back and bite. Ive also read that this particular brand and model of pump is notorious and could also be the problem.

Below are pics of my system. Notice the large pipe coming down to feed the pump and then the outlet goes up to some sort of exchange before sending water onwards.

My questions are - see the supply to the system thats at the pump outlet (bottom pic) - should that be on with the pump ? If I leave it off I still have pressure but the pump kicks in instantly with this recurring issue whereas when I leave it on they seem to compliment each other. I also find that it works perfectly fine with the pump switched off - making me wonder if it was worth doing at all.

Sorry for the long post - tldr - does this setup look right? Do I have a leak or just a rubbish pump? Also; is there any way I can remove the pump altogether without having to cap the old inlet and outlet ports? I have a valve on the inlet I can use to switch it off (1st pic) but looks like the outlet will gush water as I can't see anywhere to block it.

Thanks for reading all.

Calahonda52 · 11-06-2024 11:47pm

This is complete boXXllox

Plumber then came and checked house and said it's ok that it's normal as houses get older

He might leak as he gets older

Does the pump have a pressure vessel?

Can you close off the pipe(s) from from the pump?

FGR · 11-06-2024 11:58pm

My thoughts exactly re: normal for pump to cycle like this.

I can close the water feed to the pump and I can close the additional feed after the pump too.

The pump has a small precharge tank set to 2.1 bar as grundfos recommend 70% of the actual charge on the pump which is 3 bar.

There's also two tanks - one white and one red seperate to the pump. I presume one of these is another expansion tank but I can't measure anything from it.

Thanks again for taking the time to read and help.

ongarite · 12-06-2024 12:11am

More than likely one of the expansion vessel has failed.

There will be a valve like a bicycle valve on top. If you press in the valve and water comes out, then the internal rubber diaphragm has failed & will be causing pump to cycle.

FGR · 12-06-2024 12:20am

There's a valve on the front of the pump alright. Is that the one you're referring to?

I'll drain it tomorrow and check the pressure.

If it is the pump - is there any come back at all? This is a warranty replacement that is 4 years old now - id have expected much longer from a €700 pump.

Don't get me wrong. I'd much rather the pump being the culprit than a leak in the system.

I also re-primed the pump in the last half hour and no cycling. I know it's only a 5/6 hour stopgap before it comes back.

Calahonda52 · 12-06-2024 7:32am

https://www.boards.ie/discussion/comment/122248647#Comment_122248647

the white is for the DHW cylinder and the red is for your heating

Does the pump keep the CH topped up or how is that done: there should not be a permanent open connection

Scala 2 pump cycling every 15 mins

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