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if you're getting a good flow out the hot taps the plate aint scaled. if as you said you follow the logic diagram using sw1 and sw2 you can bring up the hot water flow temp as the thermistor is reading it. if you, re getting intermittant 85c readout its more than likely a thermistor fault which is common on boilermates. changed loads of these
 
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@garygvl so you wouldn’t do both together whist on site ? You would charge the customer another call out when the other one goes?

I’m talking about both sensor by the way not the heat exchanger. My first post sounds confusing. My bad. I deserve the dislike for not explaining.
 
@garygvl so you wouldn’t do both together whist on site ? You would charge the customer another call out when the other one goes?
asked the question do you have a good flow rate from hot taps. if you have wouldnt change the plate. from previous on these use the readouts when running the hot tap its more than likely the thm. why would i charge them for a plate thats not needed. if i was stood in front of it i would know
 
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asked the question do you have a good flow rate from hot taps. if you have wouldnt change the plate. from previous on these use the readouts when running the hot tap its more than likely the thm. why would i charge them for a plate thats not needed. if i was stood in front of it i would know
I didn’t mean the plate mate. I meant both sensors.
 
The PHE and DHW sensors. Have always done them together.
why you changing two sensors
I’m not. The OP said for £20.00 a thermista he was going to get it changed. I didn’t suggest changing it at all. All I said was I would do the DHW and PHE sensor at the same time if you are doing the one.
 
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The PHE and DHW sensors. Have always done them together.

I’m not. The OP said for £20.00 a thermista he was going to get it changed. I didn’t suggest changing it at all. All I said was I would do the DHW and PHE sensor at the same time if you are doing the one.
phe and dhw are both the same sensor so you could just buy one and watch the sensor readouts to determine which one is faulty. never had to change two before
 
nowt wrong with a bit of belt and braces just never believed in changin parts for parts sake
Fully agree. If I am honest it is only because we had a massive estate in Telford that had 100s of them when I was on the books with a company and that is what they requested we did. The main problem we had was with these sensors. Just think it was a piece of mind thing for them and it has stuck with me.
 
The PHE and DHW sensors. Have always done them together.

I’m not. The OP said for £20.00 a thermista he was going to get it changed. I didn’t suggest changing it at all. All I said was I would do the DHW and PHE sensor at the same time if you are doing the one.
Yeah I’d change both, might as well for £15 or £20. Sounds like customer has pretty much had enough already 🙂
 
There are two big estates round my neck of the woods fitted with boiler mates, Around 250 of them in total. 8 times out of 10 it is the sensor which we find at fault. We also swap them both out at the same time and we change them routinely on its 5 year service as experience has taught us that they don't last much longer. We explain it to the customer as like changing their spark plugs on a car. They may still work ok for now but almost certainly are not performing at there best and may fail at any time. the next most common thing is the pump head needs changing. Also never had to change out the plate they are quite good with decent ports and good flow through and very rarely scale up. but I am in Yorkshire with lovey soft Dales filtered water so scale is hardly ever a problem around here.
 
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Also forgot to mention that it is very important to bleed all three pumps and all the vents as air can cause intermittent lockouts and overheating problems they are very sensitive to trapped air in the unit.
 
Also forgot to mention that it is very important to bleed all three pumps and all the vents as air can cause intermittent lockouts and overheating problems they are very sensitive to trapped air in the unit.
I’ve had this on one. Didn’t realise until the 3rd visit. So annoying.
 
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