Water pump runs for around 2 seconds every 20 mins

[Mitchellmoxo]

As title above, and I noticed today whilst working in the engine bay when it runs that some water comes out of the expansion valve on the calorifier. Is there anything I can do to stop this?

 

Regards

Mitch

[b0atman]

turn Knob on the calorifier a few times to re seat it.

[Phil Ambrose]

Turn down the pressure on your water pump a little.

Phil

[Mitchellmoxo]

Will try re seating the knob how do I adjust the pressure? Thanks for fast replies

[Claude]

It depends on the pump some have a screw on the pump head to adjust pressure. You need to look at the instructions for your pump to see if the pressure is adjustable.

 

The problem could just be scale on the calorifier PRV, but if you have a NRV in the system to prevent hot water backing up the cold feed pipe then this means than in effect your calorifier is a pressure vessel with limited room for hot water expansion apart from the calorifier itself and the hot water pipes.

 

For this reason many people fit a hot water expansion vessel (which can just be a second accumulator tank) Td in after the NRV on the cold feed to the calorifier or on the hot water pipe that comes out of the calorifier. From memory I think it should have a minimum of about 8% of the volume of your calorifier - so if you have a 60 litre calorifier you'd need a minimum 5 litre expansion vessel.

 

* For reference: If you have one your accumulator tank it should be set at a few psi below your pump's cut-in pressure, while a hot water expansion vessel should be set to a few psi above the water pump's cut-out pressure. Bot set with a tyre pressure gauge with the water pump switched off and the taps open.

 

But try reseating the NRV on your calorifier or reducing the pump pressure first - if those work it's a lot easier.

[trackman]

If you buy an expansion vessel make sure it's one made for fresh water, not for a heating circuit.

The ones for heating assume that the water in them will be full of corrosion inhibitor and if it isn't they rot and fail quickly. Clearly this is what happens when one is used on a fresh water supply.

I know, I was supplied the wrong kind by a well known chandlers in the Midlands even though they knew what it was to be used for!

I had to replace it after less than a year.

[Mitchellmoxo]

Thank you for advice room for expansion vessel is tight as of where the calorifier is so I am going to have to think of a solution!

[Sea Dog]

Has it always done this? If it has, it could be down to poor system design and it may need revising (by adding an accumulator or whatever). However, if was working perfectly well before, something has gone duff or needs adjusting. Make sure what's already fitted is working properly before you embark on a redesign.

[Iain_S]

Thank you for advice room for expansion vessel is tight as of where the calorifier is so I am going to have to think of a solution!

 

It doesn't have to be right next to the calorifier; anywhere on the hot water pipery will do.

[Claude]

If you buy an expansion vessel make sure it's one made for fresh water, not for a heating circuit.

The ones for heating assume that the water in them will be full of corrosion inhibitor and if it isn't they rot and fail quickly. Clearly this is what happens when one is used on a fresh water supply.

I know, I was supplied the wrong kind by a well known chandlers in the Midlands even though they knew what it was to be used for!

I had to replace it after less than a year.

 

Yes, same happened to me. Mine lasted about 4 years though.

Thank you for advice room for expansion vessel is tight as of where the calorifier is so I am going to have to think of a solution!

 

You don't have to fit an expansion vessel - you could just get rid of the non-return valve on the cold water feed to the calorifier (assuming you have one fitted). Many people don't have NRVs, but then you may waste energy heating up the cold pipe.

Edited May 13, 2016 by Claude

[ditchcrawler]

 

Yes, same happened to me. Mine lasted about 4 years though.

 

You don't have to fit an expansion vessel - you could just get rid of the non-return valve on the cold water feed to the calorifier (assuming you have one fitted). Many people don't have NRVs, but then you may waste energy heating up the cold pipe.

And may even get warm water out of your cold water taps

[boat fan]

And may even get warm water out of your cold water taps

 

 

My thoughts exactly.