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Heating element replacement Vokera 25S

xboxdad

Hi everyone,

I'm wondering if it's worth replacing the "heating element" in a Vokera 25S.

Bord Gais found it's at 75% efficiency only due to hard water / limescale. They said it's the "heating element". I'm guessing that's the "heat exchanger".

Should I just live with it or it's economical to get a new one installed?

They said the cost of a replacement wouldn't be far from the cost of a new boiler.

Thank you.

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Lenar3556

Is it a combi boiler?

xboxdad

https://www.boards.ie/discussion/comment/123312800#Comment_123312800

Thank you for your response.

It's not a combi boiler, it's a "system gas boiler".

Lenar3556

Hard Water / Limescale shouldn’t arise in a sealed heating system unless there are leaks and constant re-filling. In which case these need to be resolved in the first instance.

I would be interested to know where the 75% is coming from. Is that a combustion efficiency reading from a flue gas analysis? - Did he give you a printout showing the figures leading to this? If so could you post a photo?

Replacing a heat exchanger may be viable if the part is readily available. But you need a clearer picture of what is going on before making a decision.

xboxdad

https://www.boards.ie/discussion/comment/123313191#Comment_123313191

Thanks again.

So this I what I got. I think I see 18.3kW written on the right hand side.

I'm guessing that's the only trace of the things he told me.

The boiler is supposed to be able to output 24.45kW according to Google and 18.3kW is 75% of that.

Lenar3556

It’s not great paperwork. Any technician should be able to produce either a print out or digital report from the analyser, which would have provided a clearer picture.

GR (18.3) might mean Gas Rate, which is a rather rudimentary test to ascertain the rate at which the applicance is consuming gas. There could be several reasons why the boiler appears to be using less gas than would be required to deliver its nameplate output, but regardless this tells us nothing about efficiency.

I wouldn’t be taking any action unless there is an obvious issue with the performance of the system. Is the heat exchanger being cleaned at all in the course of these services?

John.G

All Vokera boilers, on firing up, restrict (or used to) the output to 75% of maximum for 10 minutes, the output, if required, is then increased to its maximum over the next 10 minutes. So maybe those final readings were taken within 10 minutes of refiring, 18.3/24.45, 74.85%, say 75%.

Its output is actually restriced for 15 minutes.

xboxdad

https://www.boards.ie/discussion/comment/123314876#Comment_123314876

I don't know if any of the companies I used to do these annual checks did any cleaning. (used Electric Ireland, Bord Gais, Vokera themselves and others)

This latest service was done as part of the Bord Gais boiler care service I subscribed to.

Thank you.

xboxdad

https://www.boards.ie/discussion/comment/123314950#Comment_123314950

Thank you. Very interesting! I hope that's what happened.