Heatrae Sadia "Seven" immersion heater - very slow

[Knucklehead]

Hi, any help would be very much appreciated!
I have recently moved into an all-electric house (no gas), which has Economy 7. Hot water is provided by a direct boiler labelled Heatrae Sadia "Seven". It is also stamped with what is probably its installation date of 1988.

The problem I have is that when using any of the hot water taps in the house, the flow is little better than a trickle (takes 25 minutes to run a fairly shallow bath!).

I have changed the tap heads on the bath etc. No difference. I've changed the gate valve that sit between the cistern and the hot water tank. Again, no difference. The only bit in between is the Heatrae, so I guess that's where the problem lies.

The house itself was built in 1988. Any ideas about what to try next?

Many thanks.

 

[gasafengineer]

Could be partial air lock , many of these type systems were fitted in flats wherby static head is low , wouldn't be surprised to see foam insulation partially blocking hot water draw off , this was sometimes the case when the installer removed foam insulation from around immersion heater boss on install.

 

[Knucklehead]

Many thanks. we're in a house rather than a flat, but foam insulation blocking the outlet is a distinct possibility! Will check.