help with ecoTEC valliant 831 and heating

[Johntheo5]

The dT is now approaching "normal" IMO.

Is the stuck screw the bypass screw, if so where is the bypassing going to?
What are your pump and power settings now?
Is the displayed power level in the LH corner of the RH photo based on the d.00 power output?, if so, handy to see your actual heat demand by reducing d.00 until the level reaches 100% in the display.
I wonder how may Vaillant models have that flow strainer and how many service people know about it.

 

[MW9]

"Is the stuck screw the bypass screw, if so where is the bypassing going to?"
yes it is the bypass screw to regulate the pressure, i think it is stuck in middle position, as default settings

"What are your pump and power settings now?"
power output is on Auto, pump was at 100% but I switch it to auto now and will see how the heating will come on in the morning from cold start

"Is the displayed power level in the LH corner of the RH photo based on the d.00 power output?, if so, handy to see your actual heat demand by reducing d.00 until the level reaches 100% in the display."

power output is on Auto and it must have been higher as it was just about 5-10 min since starting the heating so a lot of water to heat up.

"... flow strainer and how many service people know about it."
by the look of it not many and I think it might be just mainly for the systems without magnetic filter and if you have one I think it just causes issues in the long run. I was lucky enough to get a call from a guy who knew about it when I raised a request on valiant website for the service companies to contact me to fix my boiler and he offered this advise to me and sent me video so I can show it to my service guy.

its hard to make a good photo of those LCD as they flicker to camera like LED lights on the car

 

[MW9]

I had the heating set for today morning to test and it was set with pump on Auto, and all the radiators heat up, I even lowered the flow temp to 65 from 75 not sure if I will go lower as I have hot water tank which mix cold water from the loft, so to be safe with legionella I think I will leave it on 65.

I have just finished replacing windows to triple glaze and I've done external wall insulation so I think this winter will be first I won't complain about temps since we moved in.

I'm still gonna change that valve which have bypass screw stuck and get some better TRV's.

I think the main issue were:
- sludge in radiators which x800 helped and dissolved some stuff inside
- blocked or partly blocked filter on the flow pipe in the boiler which caused boiler to cycle all the time and hot water was returning via bypass
- and I think the bypass valve is partly broken


I wonder now if I would get all radiators to heat up with all lock shield open for balancing but I'm not touching anything till next time I need to drain the system. making notes of all the valve settings for next time.

 

[Johntheo5]

You might invest in a thermal gun to give you a reasonable idea of the rad return temps. I don't have any balancing and all the rads heat up fine, I have a OF boiler with a external Wilo Yonos Pico 6M pump set to a PP (proportional pressure) setting of 4.6M which results in a pump head of ~ 3.6m with all rads open but then modulates down to give ~ 2.5/2.8M when the TRVs are closing in.

Does that bypass screw just look like that, a fixed adjustable by pass that will pass more or less depending on the pump head?.

 

[MW9]

I have the infrared gun for temp but on some silver radiators it does not work, I have one as well with probes which I can stick with masking tape might use that but all radiators heat now roughly at the same time so unless I feel cold in winter I think i will leave it like this now

the bypass screw looks like this

Vaillant Bypass Valve Assembly 178980

Vaillant Bypass Valve Assembly for installation in eco TEC VU (condensing), eco TEC VUI (condensing), eco TEC VUW (condensing), eco FIT VU (condensing), Guernsey/Jersey only (condensing), eco FIT VUW (condensing) and Home (condensing) appliances. The bypass valve, or flow regulator, controls the...

www.cityplumbing.co.uk

and it should freely turn right or left but its stuck

 

[Johntheo5]

It says here that the canoe filter is to protect the PHE so wonder has it any effect on the CH?.

"Canoe filter is a canoe shaped filter (hence the nick name) located before the flow goes into the plate heat exchanger, to protect the plate heat exchanger from blocking."

 

[MW9]

Might just get it as well then and put new one when I replace the bypass valve

The other engineer said it can run without but obviously it is there to do something I wonder how often it will get block as this is something I won’t be touching.

 

[MW9]

as an update to all following this post or to whoever will have similar issue

Today engineer have managed to changed the parts

Diverter : 0020132682

Filter : 179030

And the boiler behave much better or as it should as I never seen it working correctly since I moved in here

Radiators get nice and hot, the flow temp raise slowly and steady, it was for long time at 30degree when we started from cold where before it was just raising, the diffrance in flow and return when it’s starting from cold is 20-18 degree which I never seen before, the difference drops once all radiators are hot but it’s probably as they don’t lose as much temp now as it is not cold outside

And the return pipe actually feels to the touch now to what it shows on the d.41

The valve looked dirty inside so even though it looked like it worked it didn’t do what it supposed to do.

Fingers crossed