Vokera Linea 28 pressure problem

[andy40]

Last year I moved into a house with a new-ish Vokera Linea 28 combi boiler. CH works a treat with no problems, there's a slight pressure loss over time, but within limits, but the problem is the hot water pressure. The hot water comes out of any tap very slowly, and it is impossible to run two hot taps at a time (not enough pressure). There is also a thermostatic mixer shower which is permanently lukewarm, which I assume is from the same problem. I've had the boiler serviced by a CORGI engineer and he has assured me its OK, and said it might be down to low mains pressure. However, the water board came and measured the pressure, and it was enough for a 3-storey house! So no problems there. I'm really at a dead end to find out what the problem is. My thinking is that it HAS to be something to do with the boiler as there's nothing else it can be. Any ideas anyone?

 

[Agile]

Unfortunately its not possible for me to comment on emotional statements. I need scientific evidence!

Could you measure the hot water flow rate in litres per minute?

Tony

 

[gas4you]

If you are sure you have good flow rate and pressure and you live in a hard water area I would suspect the plate heat exchanger is partially blocked. I've found this a very common problem on these.

 

[nickso]

as dave says or the restrictor is blocked.

follow the pipe from the dhw flow switch and disconnect the union on the stainless pipe just above the plate h/e. there be the restrictor jaaackk! (was watching the new pirates film last night and im now speaking like capt barbossa all day )

 

[andy40]

Thanks alot for all this. My hot water flow rate is 5 litres per minute, and my cold water flow rate is nearer 20 litres per minute, so I guess there is some blockage!! Is cleaning the heat exchanger a major job i.e. expensive?!

 

[ChrisR]

Not particularly, but start by checking/removing the restrictor.

 

[andy40]

Bearing in mind you are talking to a COMPLETE novice, could anyone give me exact instructions as to how I can remove the restrictor i.e. what do I have to turn off etc. Cheers.

 

[nickso]

Bearing in mind you are talking to a COMPLETE novice, could anyone give me exact instructions as to how I can remove the restrictor i.e. what do I have to turn off etc. Cheers.

turn off mains water or turn off at black switch under boiler. leave a hot water tap open then............

as dave says or the restrictor is blocked.

follow the pipe from the dhw flow switch and disconnect the union on the stainless pipe just above the plate h/e. there be the restrictor jaaackk! (was watching the new pirates film last night and im now speaking like capt barbossa all day )

flow switch is the black and red thing on the right hand side above the black switch you turned off

 

[andy40]

I'm still pursuing the restrictor, but could anyone tell me what a boiler service actually consists of? The reason I ask is that why didn't the engineer notice the lack of hot water pressure when he serviced it? Is there a generic checklist of things they go through?
Thanks again si far for all your help.