Pulsing water problem

[st3v3]

I have a problem that has only started this year, it was fine last year and has been installed for some time.

The setup is:

Shurflo pump with integrated pressure switch
Morco primo instantaneous Gas water heater
Domestic kitchen tap and mixer shower.

Running cold from the kitchen is fine
Running the shower, the pump turns on and off

Turning the kitchen cold tap on at the same time as the shower makes the pump run continuously.

I've removed the shower mixer, blanked the cold and left the hot open, the pump still pulses.

So, I'm left with the water heater is now causing an obstruction or the pressure switch has gone over sensitive.

Anyone had anything similar?

I know @n brown has had a lot of experience with these heaters... Any thoughts mate?

 

[QFour]

Ours does that. Its a restriction as it passes through the water heater. You could fit an expansion vessel there is one for MHs. It has a rubber diaphragm inside and helps stop the pulsing or turn the water pressure down.

 

[st3v3]

Ours does that. Its a restriction as it passes through the water heater. You could fit an expansion vessel there is one for MHs. It has a rubber diaphragm inside and helps stop the pulsing or turn the water pressure down.

Thanks. I'm just confused as to what has changed. It's worked fine for ages...

 

[st3v3]

I'm just having a read and it seems like the switch may be adjustable... I'll go look.

 

[QFour]

The switches are adjustable. The water heater is probably getting fired up inside unless you have cleaned it recently with white wine vinegar.

 

[Lee]

Steve
If the problem continues, I think I've got an expansion vessel in the garage.
Let me know if you want it and I'll look at the weekend, when I get home.

 

[st3v3]

Steve
If the problem continues, I think I've got an expansion vessel in the garage.
Let me know if you want it and I'll look at the weekend, when I get home.

Yes please Lee, thanks.

 

[n brown]

Hi Steve ,don't know why it's doing it but an expansion vessel should help .all the pumps i fitted in portugal had them included
any problems like that with the water heaters wasusually down to furring up ,as QFour said . normally i'd say flush with muriatic acid ,easy to get abroad ,not here though

 

[Thistle]

With and without an expansion vessel:

 

[Millie Master]

Thanks. I'm just confused as to what has changed. It's worked fine for ages...

That problem could be called by the system gradually calcing up with lime scale, it helps if you run a thorough load and rinse with a strong solution of a product such as Puriclean or similar.

 

[Fazerloz]

Mine does exactly the same and has done since I replaced the old pump, I just ignore it. The boiler is as clean as a whistle inside as it was only last year that was out as well.