Viessmann Weather Compensation

[monkeysballs]

on the pump subject mine has been on solid for a month (except 2 points where i turned the power off )

 

[vulcancontinental]

thats the opposite of my issue with my setback set it thinks it needs to heat when it doesnt take this morning it came on at 5:40 thinking it needed to top up the heating the setback temp was set to 14c! outside it was 6.2c yet the coldest room in the house (that i care about) was 18c! the absolute coldest was 17c (thats the utility with open fan vent)

if i have it set to a sensible setback temp my heating is on alot more than it should be and id like to use the correct setback temp of 17c so about 2c less than my daytime temp the issue is my house just doesnt loose heat that fast it performs more like its got UFH but it doesnt

That situation is exactly what Viessmann says it prevents. If you're on Facebook join Heating System Design group and explain the situation, there are Viessmann experts residing there. Or try the HeatGeeks Heating help for home owners, similar thing.

 

[monkeysballs]

not on FB i called andrew millward the other day and had a long chat and he couldnt understand it really either. will try the Heat geek forum

 

[monkeysballs]

ah thats fb too

 

[vulcancontinental]

not on FB i called andrew millward the other day and had a long chat and he couldnt understand it really either. will try the Heat geek forum

If he doesn't understand it you have a real issue, he worships at the temple of the V200, a real disciple.

 

[monkeysballs]

to be fair he was on the way to a client and im at the other end of the country so it was nice of him to even pick up seeing as he wont get any money out of it more than likely!

 

[tech749]

Thanks, the reason the pump is running all the time is probably because the minimum output of the boiler is greater than the heating demand which means the burner will cut out when the flow temperature exceeds target temp + 5C, the burner will then refire when the anticycle time has elapsed and when/if the flow temperature is target temperature - 5C.
So do you set the WC curve?, if so then the boiler possibly sets the level depending on the requested room temperature.

What is the rated output of your boiler and what is its minimum output?
I see the minimum output of all these 050 boilers is 3.0kw.

It mentions two ratings in the manual as follows, Rated Heat Outputs : 50/30 C - 3.2-19 kw : 80/60 C 2.9-17.1 kw : DHW - 25 Kw. But on their web site it says this - Output Rating : 3.2-25kW and a DHW output of 29.6kW. Not sure why its different.

The heating curve was initially set by the installer, and he just said try it and adjust accordingly. I haven't had to as its warm in the house. The boiler temperature is set at 20 deg from the factory, and I noticed that if you increase/decrease that setting on the boiler, it adjusts the heating curve up or down. It is still set with 1.4 slope and level 0, its just that the flow temperatures have changed accordingly, because it needs to be warmer if I increase the boiler temp, and vice versa.

I understand why pump is running, it has to keep the water flowing round the radiators to keep the room at temperature. As you said the boiler burner will then fire as the water gets cooler and go off when temperature is reached, but still have to pump through the system.

 

[monkeysballs]

another issue with my install the installer but the wc ntc on the east side of the house rather than the north side yes its shaded most of the time until the sun hits it then it gets warm! i need to get it moved but that means ladders

 

[tech749]

thats the opposite of my issue with my setback set it thinks it needs to heat when it doesnt take this morning it came on at 5:40 thinking it needed to top up the heating the setback temp was set to 14c! outside it was 6.2c yet the coldest room in the house (that i care about) was 18c! the absolute coldest was 17c (thats the utility with open fan vent)

if i have it set to a sensible setback temp my heating is on alot more than it should be and id like to use the correct setback temp of 17c so about 2c less than my daytime temp the issue is my house just doesnt loose heat that fast it performs more like its got UFH but it doesnt

Have you tried looking at second hand controller, I read somewhere that you can use a 200 or 300 controller. Just seen this, any good? https://www.ebay.co.uk/itm/16643338...816459697485&abcId=9303862&merchantid=6995734

 

[tech749]

another issue with my install the installer but the wc ntc on the east side of the house rather than the north side yes its shaded most of the time until the sun hits it then it gets warm! i need to get it moved but that means ladders View attachment 322423

If the east side is more accessible, can you fit some kind of shade to it? Metal plate screwed to wall or something?

 

[monkeysballs]

honestly its less accessible and i have no idea why he fitted it there!
doesnt look like that one will work the wired 200e will work but wired and not that much less, id have bought the 300e months ago but apparently no stock likely until feb!

 

[tech749]

honestly its less accessible and i have no idea why he fitted it there!
doesnt look like that one will work the wired 200e will work but wired and not that much less, id have bought the 300e months ago but apparently no stock likely until feb!

Ok, didn't realise the tech details of controller
It says in all the manuals sensor should be North facing, if it's a recent install can't you get him back to reinstall it in correct position free of charge, as it's clearly an error on his part.

 

[Johntheo5]

thats the opposite of my issue with my setback set it thinks it needs to heat when it doesnt take this morning it came on at 5:40 thinking it needed to top up the heating the setback temp was set to 14c! outside it was 6.2c yet the coldest room in the house (that i care about) was 18c! the absolute coldest was 17c (thats the utility with open fan vent)

if i have it set to a sensible setback temp my heating is on alot more than it should be and id like to use the correct setback temp of 17c so about 2c less than my daytime temp the issue is my house just doesnt loose heat that fast it performs more like its got UFH but it doesnt

Are there any trends out there showing the "room" temperature plotted against the OT temperature from people who are happy (apart from you?) with WC only control , NO roomstat.

 

[monkeysballs]

dunno

ive just adjusted my curve and throttled my rads to see if i can get a better return temp as last night as event though it got down to 1c with it trying to maintain 13c we still woke to lowest temp being 17.5c

 

[tech749]

Are there any trends out there showing the "room" temperature plotted against the OT temperature from people who are happy (apart from you?) with WC only control , NO roomstat.

Even though I have a room stat, effectively I am still running on WC only, the only difference being the boiler is off overnight as the temperature in the house is normally warm enough, last night it was 18.5 deg with OT of 1 deg so boiler doesn't kick in. During the day the room stat doesn't do anything as it's set above the highest temp that the room gets to (20 deg).