Valliant ecotec 837 problem?

[liquidfusionv]

Hi All,

I have a Vaillant Ecotec Plus 837 installed 5 months ago. The hot water works fine but all the radiators are only lukewarm even though I have set the thermostat to 35 degs and the flow temperature to 75 degs. I have checked each radiator and there is no air. The flow temperature does not seem to go above 36 degs in the first 15 minutes or so. I have set D.0 to 16 as my calculations of total radiator output is 16kw (13 radiators).

The boiler could take an hour before the flow temperature would reach somewhere around 50 degs, so it rises very slowly. The radiator symbol just constantly flashes.

When I press 2 buttons and activate something called 'Chinmey sweep', the radiators heats up within minutes.

Sometimes when I switch the boiler off and on again, it sometimes fires up instantly heating up the radiators to hot.

Is this in ecomode or something?
Any suggestions to what the problem could be?

Thanks

 

[simond]

I would check that there is no external bypass to the system.

Failing that I would reset the boiler to defaults, software wise.

This range rating obsession we seem to have on this forum is rather pointless, by lowering the maximum heat output you are not changing the lowest output at all, which is fixed. In other words, the boiler will still modulate down to around 12Kw (from memory) as a minimum, whether you have it set for 30Kw or 16Kw max output.

You haven't mentioned what controls you have. Weather compensation would give the results you describe.

 

[liquidfusionv]

Thanks, I will try a software reset and play around with it to see if it fires up instantly heating the rads to hot.
I have a horstmann HRT3 which seems to be going off and on every 10 minutes, but the rads only feel luke warm again.

 

[liquidfusionv]

I have reset the boiler back to factory settings and adjusted hot water target to 65c, and CH target to 75c only. Nothing else
I had called Valliant earlier and they were the ones that suggested I change d.0 to 16 which I did, but hasn't made a difference.

Any other suggestions please?

 

[TCCHeating]

I have a horstmann HRT3 which seems to be going off and on every 10 minutes, but the rads only feel luke warm again.

There lies the problem. When the boiler first fires up. It will stay in minimum for many minutes before ramping up. If the thermostat is turning on and off every 10 minutes, this cycle will keep repeating, meaning the boiler never has a chance to operate at full output for a significant amount of time. You need to get the installer back to determine why the thermostat is behaving in this way

 

[liquidfusionv]

Thanks, I been doing a lot of research into this problem and came across this:

http://www.ukplumbersforums.co.uk/c...05-replace-hortsmann-hrt3-honeywell-dt90.html

It describes the stat firing up the boiler when temps drop 0.5c and switches off when it reaches the set temp.
I'm not sure if I have the same problem with the stat being dodgy so thinking of replacing it with the honeywell DT90.

It could also be the rads warming up luke warm enough for it to trigger the +0.5c and switching itself off again, although this 1 problem not the main.

The main issue is when I crank it all the way up to 35c and leave it on for 20 minutes, it still doesn't want to demand a higher flow rate than 36c.
I suspect something wrong with the boiler but the installer told me to speak to Valliant which I did this afternoon, and them telling me I had to set d.0

After doing that I thought it had fixed itself but maybe it was just a one off, same problems again when I test.

 

[muggles]

Is your HRT3 too close to a radiator? If so, that would explain why it's going on and off all the time. Alternatively, the boiler could be in anti-cycling mode as it's so massively oversized for the system. You can check this by pressing the "i" key on the control panel when it's in the "fault" condition. If it comes up with S.8 then it's in anti-cycling mode

 

[liquidfusionv]

I knew someone was going to ask that but I forgot to mention it
It's not close enough for a stat to notice a temperature difference straight away.

When I check the status it's always s.04 Live status - 'Burner on'

I've even changed it down to 2 minutes for the anti-cycling mode just to test.

 

[liquidfusionv]

Also, the slightest touch (not twisting it) of the stat causes it to fire up the boiler, is it meant to do that?

 

[TCCHeating]

Best thing to do is to put a link wire at the room stat so that it is permenantly on. (if your not electrics savvy then get an engineer to do it). If the boiler works ok after you have done this then the room stat is at fault. If it still doesnt heat up properly, the boiler is at fault. The fact that it works ok when in chimney sweep mode suggests there is no problem with the system, so it could only be a settings or pcb fault in the boiler.

 

[ScottishGasMan]

Range Rating the boiler IS the correct thing to do. I cant understand people assuming it will all sort its self out. These boilers wont just range down bacuse you have a small system, they only modulate when the flow temp is within 5 degrees of target, which means they can over heat and then go into a low fire waiting mode.

Range Rate D.0 to 16 kw again, a boiler this big needs to be given a maximum limit to its output to the radiators.

Your problem is as mentioned the stat. All the ecotec models now will fire on minimum for 5 minutes to circulate system water before ramping up, if you run a tap every 5min or the stat turns it on and off every 5 min, the boiler will never go to a higher fire, circulation seems fine as the chimney sweep mode has worked (which overrides the call from the stat)

 

[liquidfusionv]

Appreciate all the help guys!
I will range rate the boiler as suggested, and change the stat to see if it makes a difference.
I've also dropped the anti-cycling mode from 20 minutes to 2 minutes, if anyone can see a problem with that please let me know. I know it's meant to prolong the life of the boiler but I'm sure they aren't that fragile.

 

[ScottishGasMan]

Yea, put the anti cycle back up to 20 or at minimum 10, you set it to 2 minute the boiler will be cycling on and off like mad, (you havent actually set it to 2 min using that setting, you have modified the position of the anti cycle on a curve that is based on flow temp which is fine for UFH running 35 degrees, yours set at 70*c odds will cause issues

 

[simond]

You've already taken the range rating off and proved that is a complete red herring. Now someone has puffed up their chest and you are going to put it back on...........welcome to the forum.

Boiler has already been set to defaults so it isn't the anti cycle either.......

 

[ScottishGasMan]

Never mind, actually going by the charts for that one it wont make much odds where you set the anti cycle sorry.