ATAG A325ECX: Hot water but no Central Heating. Any ideas?

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UphillPhil

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Have called the guy who installed it to come and take a look at the beast, but in the meantime does anyone have any ideas based on the following symptoms?

ATAG A325ECX condensing boiler installed ~18 months ago. Heating system is a three loop job, each loop guarded by a valve controlled by a Honeywell radio control & remote thermostat pair.

The boiler fires up and delivers piping hot water, but refuses to fire up in response to a request for CH from the thermostats. The little rad symbol appears on the boiler control panel, so it is receiving the request for heat, but refusing to fire up. There are no errors reported by the boiler.

After running the hot water tap for a few minutes, both the CH inflow & outflow pipes become warm, especially the return pipe between the expansion tank and the main body of the boiler.

Poking the boiler CP after running the hot water tap reveals that it believes that the temperature of the CH inflow & outflow are both simultaneously almost equal & high - often around 55 degreesC. I suspect that this is why the boiler isn’t even bothering to fire up - it thinks the hot water return temperature means that there isn’t any point.

Any thoughts on a likely cause? Some googling around suggests that the diverter valve is a likely cause. Any other possibilities, or things I can do to test this hypothesis?

cheers all, Phil
 
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Just in case anyone suggests it, I have trundled round and bled all the rads just in case & apart from a little air in the very top rad they were all full to the brim. Have also checked that the valves are doing their thing in response to heat request from the thermostats & they appear to be turning. I suppose all three could have failed, but seems unlikely! Also the installer put small drain taps on the inflow & outflow pipes to the boiler - these will drain water when the valves are open, but not when closed, which implies that the valves are doing their thing.
 
I only just looked at your thread.

I suspect most others here did not look at it because most don't recognise your model or see very many.

The symptoms you describe are typical of what happens when the diverter valve is jammed on DHW on a combi.

Pity I did not see it before to say what I expected it to be.

I worry that the system may not have been cleaned very well at installation.

Did the makers replace under warranty or the installer just did something to make it work again?

What cause did he tell you for it failing?

Tony
 
He took the diverter actuator off and put it through it’s paces: It happily winds all the way in one direction, then refuses to go back the other, so it seems likely that it’s just the actuator. He was sure that makers will replace under warranty, though haven’t had confirmation of that yet.

System was powerflushed when boiler installed & almost no gunk on the Magnaclean when I looked at it. Which is no guarantee of anything of course!
 
Hope he left it in DHW mode for you!

Mag filters are good on a dirty system, but after power flushing should not be required!

I only fit them if client insists. Many use them as an alternative to proper cleaning.

The makers may insist on sending their own engineers. Others will agree to just send the part ( which I prefer as it sorts out the boiler faster! ).

Tony
 
It’s stuck in DHW mode regardless :)

Installer didn’t think manufacturer would quibble about the part. Will report back.
 
Just updating to confirm that Atag replaced the failed part with no quibbles whatsoever. After some confusion where they sent entirely the wrong part first time around...
 
Agile said:
I only just looked at your thread.

I suspect most others here did not look at it because most don't recognise your model or see very many.

The symptoms you describe are typical of what happens when the diverter valve is jammed on DHW on a combi.

Pity I did not see it before to say what I expected it to be.

I worry that the system may not have been cleaned very well at installation.

Did the makers replace under warranty or the installer just did something to make it work again?

What cause did he tell you for it failing?

Tony
Click to expand...
Pity you couldn't explain how a pump plan should be wired when using relays instead of dedicated control box.
Why do you feel the need to constantly put yourself upon a pedestal?
 
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