Hot tap(s) violent juddering fully open (small water heater)

[RoyalCrabs]

Hey,

Never had to work with what I think may be an air lock before , heres the back story ;

Local village shop owner said a hot tap in shops upstairs bathroom was left on slightly over night (1 of 3 appliances fitted to a water heater) and from that morning on wards the 2 KITCHEN hot taps in another room 'judder' violently when fully or half / full open.
If you open them both fully or one of them 1/4 open its fine, telling me something to do with pressure?

Heater ; Ariston Unvented Water heater with a pressure reducing valve fitted.

I dont plan on messing around with the heater itself, but if needs be do some corrective pipework or clean filters if need be.. Mainly just get an opinion from more experienced kind chaps like yourselves!

Cheers

 

[iain85]

It's Ebola. Remove taps and incinerate immediately.

 

[RoyalCrabs]

I had assumed that already but didnt want to show my intellectual prowess by stating the obvious amongst you guys.

 

[kay-jay]

Needs a tap that has a built in pressure discharge
Specific for the purpose.
Or check the water heater mi's for pressure relief arrangement.

Essentially whst is happening is as the water heats up there is expansion which needs venting somehow as the pressure increase is causing problems

 

[erj]

could be a loose washer in the tap

 

[kay-jay]

sorry i read it as undersink heater. if its a full sized unvented cylinder you need someone with a g3 card to inspect it for you

 

[RoyalCrabs]

No sorry its not a full unvented cylinder, I its just a small waterheater (does have exp. vessel & tundish though) that just feeds only 3 hot taps and this violent 'juddering' when fully opened on any of the 3 taps opened individually, started after one tap was left open over night.
Again ; APPARENTLY, this is what the customer says, I cannot back it up as 100% fact as the 'cause' of this juddery tap situation..

 

[kay-jay]

download the mi's then and read up on pressure relief discharge. you dont need g3 to do the work on 15l capacity or less.

or look at a special vent tap which purposely dribbles every so often to release the expansion

 

[RoyalCrabs]

download the mi's then and read up on pressure relief discharge. you dont need g3 to do the work on 15l capacity or less.

or look at a special vent tap which purposely dribbles every so often to release the expansion

When you say MI, do you mean manufac. instructions?
Do you reckon it built up pressure from being left on over night or caused air to get into system? Like I say it only judders when one tap is fully open (any one tap), thanks

 

[kay-jay]

When you say MI, do you mean manufac. instructions?
Do you reckon it built up pressure from being left on over night or caused air to get into system? Like I say it only judders when one tap is fully open (any one tap), thanks

Yes manu instructions.
It may be that it is only deaigned for one tap. StRting point is to get the mi's snd check the installation against them.

 

[RoyalCrabs]

Yeah I had the instructions and said nothing about violent juddering noise when hot tap is fully opened.

I had another look and forgot to take notice of a double check valve on each hot tap in the kitchen, it really does sound like its those making this pneumatic drill kinda sound. However, I un seized the basin tap (3rd appliance fed from the water heater) and when fully open it makes no noise what so ever..

 

[RoyalCrabs]

I've just remembered the term for the noise ; Water hammering.

This HAS to be double check valves right ?