Duo Tec DHW Comes on When Cold Switched Off

[arran197]

When the cold tap is switched from on to off, occasionally the boiler will briefly come on for hot water. I know it's not crossed, it's just the water hammer causing false readings on the flow sensor. Do I need to put a not return valve on the hot outlet?

 

[Ermintrude]

I would fit a water hammer arrester

 

[arran197]

Come again?

 

[tamz]

A wee expansion bottle

 

[Billy Bob Bob]

When the cold tap is switched from on to off, occasionally the boiler will briefly come on for hot water. I know it's not crossed, it's just the water hammer causing false readings on the flow sensor. Do I need to put a not return valve on the hot outlet?

you have a dead leg full of air somewhere ,find it,bleed it,problem solved

 

[arran197]

I'm wondering if it's because the kitchen has been taken out so the water is isolated to where the old sink was. I'll wait and see what happens when the new kitchen is fitted.

 

[Ermintrude]

A wee expansion bottle

Tied but it kept spraying on my legs!

 

[dmheat]

As above, shock arrestor

 

[arran197]

Had a look, there's a iso valve on the hot in the kitchen, need to vent it at some point and then test it. The house is being renovated at the moment and isn't lived in, so it's something I'll get round to doing. Got to run a gas pipe for the cooker too, all jobs that need doing.

 

[Taffman]

shock arrester will sort this

 

[arran197]

It was the kitchen pipework. It's not doing it now the new kitchen has been fitted. Thanks though.