Ecomax 824/2E wrong temp - luke warm water

[Grangey]

Hi all,

So for a few months I've been putting up with my hot water no longer being hot- just barely luke warm as frankly I'm not in a position to replace it and it's been working fine up until the NTC sensors were replaced.

Now until today theres been nothing obvious about whats happening, say the resting temp on the boiler was 20oc, you'd run a tamp and it would reach the target which is set to 65oc, but then fairly quickly start cooling down 1oc at a time before settling around the 40oc mark for a good 10-15 minutes. Wouldnt matter if the heating was on or not, or had been on or not. Occasionally in the shower it would kick back up to 65oc briefly before doing the same thing. Even more rarely, it would keep to the temp so you could have a normal shower.

Anyway today minutes ago, I noticed the boiler was sat at the reading of 61oc. Note, the central heating has not been on, nor was there any demand. The hot water had also not been running. When I saw this, I turned on the hot tap, when it quickly went up to 70oc before cooling down again...

So my theory is the boiler isn't actually detecting the right temps, thinking the water is probably much hotter than it actually is. This seems logical given it was working fine before all 3 NTCs were replaced... my issue is they've each been replaced for different reasons at least twice, so I'd rather not have to go through the same cycle again if actually this might not be the fault of one of the NTC's but an underlying issue with another component.

Can anyone confirm this is likely an NTC issue, or whether it could be a sign of something else? Be it dodgy heat exchanger?

It will take me months before I'm even close to affording to replace the boiler (which will (fairly) be 95% of plumbers opinion locally due to its age), but I could certainly find the funds to replace a key component if its 90% the likely cause. I'm just trying to avoid the "It will cost £x for the call out to diagnose the issue, then its £x per hour when we return to fit the part" etc. I'm aiming for more a "I've drained the system and here's the part, can you fit it please" when they arrive.

I should also add that at least once every fortnight the boiler would loose pressure, seemingly from the PRV for no obvious reason. Just in case this could help with what this points to (ie faulty expansion vessel).

Thanks and sorry about the essay.

 

[picasso]

Might be a blocked main heat exchanger or a problem with the gas supply, you need someone (like a registered gas installer)on site to diagnose the problem.

 

[ianmcd]

with the heating off run a hot tap then feel the heating flow and return below the boiler to see if they are getting hot

 

[Grangey]

with the heating off run a hot tap then feel the heating flow and return below the boiler to see if they are getting hot

Thanks seems you’re on to something, with CH off running the hot tap and the CH flow gets hot to touch. What does this indicate? Faulty diverter valve?

 

[ianmcd]

yes you are correct your diverter valve is passing, but I have seen a partially blocked plate heat exchanger causing the same thing

 

[ollski]

You sure the preheat isn’t on and the flow sensor failed?

 

[Grangey]

You sure the preheat isn’t on and the flow sensor failed?

Preheat is off for sure. How would I determine if the flow sensor has failed without a fault code?

Thanks all for the input so far, it does sound like a diverter valve issue, possibly linked with heat exchanger partially blocked (not sure if or why this would cause the CH Flow to heat up when only water is in demand though)

 

[ianmcd]

if you select HW only and the boiler fires when you open a hot tap then the flow sensor is fine, when the plate heat exchanger gets blocked the boiler cant transfer all the heat to the DHW and you can get some back pressure forcing water down the heating side , I think with yours it is most likely the divertor valve though

 

[Grangey]

if you select HW only and the boiler fires when you open a hot tap then the flow sensor is fine, when the plate heat exchanger gets blocked the boiler cant transfer all the heat to the DHW and you can get some back pressure forcing water down the heating side , I think with yours it is most likely the divertor valve though

Thanks Ian that makes perfect sense. I've just ordered a diverter valve so fingers crossed that sorts it.

Completely unrelated query, but I have noticed the boiler gives of a f.24 low CH pressure reading but when the boiler hits around 1.1 bar which is technically still in the green. I have to top it up above this to get the boiler active again. Is this a sensor issue or something else entirely that could be a concern (and warrants a new thread)?

 

[ianmcd]

Thanks Ian that makes perfect sense. I've just ordered a diverter valve so fingers crossed that sorts it.

Completely unrelated query, but I have noticed the boiler gives of a f.24 low CH pressure reading but when the boiler hits around 1.1 bar which is technically still in the green. I have to top it up above this to get the boiler active again. Is this a sensor issue or something else entirely that could be a concern (and warrants a new thread)?

remove the pressure sensor and clean the port and the switch, it sounds like you have a dirty system that is causing your problems, you will know when you remove the sensor if it is full of magnetite,( Black sediment)

 

[Grangey]

New diverter fitted... sadly same issue still exists

Before I go spending another not small amount of money on a head exchanger, is there anything else that could be causing this? Or is this really the only other option?

Thanks for the help so far

 

[ianmcd]

When you removed the old diverter valve was the water quality poor ?

 

[undertrained]

When the diverter energises, is it very quiet? Could be a voltage issue from pcb.

 

[Grangey]

When you removed the old diverter valve was the water quality poor ?

Nope all very clear in fairness. The pressure sensor was mucky but that was the only sign of dirt in the system. Even draining down from the rads it was pretty clear ...

 

[Grangey]

When the diverter energises, is it very quiet? Could be a voltage issue from pcb.

Hmm interesting, hard for me to say without knowing what it should sound like. Would it help if I took a video?