viessmann 050-w and viessmann generally

[Deleted member 131795]

same control options essentially, just load compensation. the cheaper baxi option would just use a cheap EPH opentherm controller and the (much) more expensive vaillant option would include their sensohome controller.

the vaillant ecotec plus was recommended to me as the best non-budget option by syzmon from urban plumbers, simply because of the modulation going as low as 2.5kw. the heat loss in my flat is about 4.8kw.

the main eco compact only goes down to about 6.7kw

but i'm not sure just how important this extra wide modulation ratio is, over it resorting to on/off control when it reaches set point.

the main is just very basic, whereas the vaillant looks completely badass, has all kinds of app control and data stuff going on, it's a fair few db quieter too, and as it'll be going in airing cupboard in bedroom, not kitchen, this might be worth the extra.

no idea i'm so confused. an extra £1000 is a lot of money, i can manage it, but i wonder how much of a difference it would really make.

 

[Knappers]

I would like to think that vaillant controls would be more effective and I'm a big fan of matching boiler and controller (except baxi)
If 'main' is running with opentherm then there probably won't be much difference and if in a cupboard then looks don't matter.
The smart choice would probably be the main.
I'd probably chose the vaillant tho coz I'm just not very smart.
(I'm sure that doesn't help)

 

[bobbyt]

I would like to think that vaillant controls would be more effective and I'm a big fan of matching boiler and controller (except baxi)
If 'main' is running with opentherm then there probably won't be much difference and if in a cupboard then looks don't matter.
The smart choice would probably be the main.
I'd probably chose the vaillant tho coz I'm just not very smart.
(I'm sure that doesn't help)

Hi,
I recently had a Viessmann 050 25kw combi fitted with weather comp and EPH controller, which provides basic on/off temperatures if required. It replaced my old Baxi with hot water tank etc.
I'm using the CH for the first time this week, and must say it is really efficient. 10 deg outside and it is modulating at 10% and using about 3kwh when burner is on, and the burner isn't on all the time. Rooms at a constant temp of 20-21 deg. Really pleased with the whole set up, saving loads of gas compared to my old boiler which was only on 8-9 hours a day, and I have this one on all day and night with reduced night temperature set on controller. Just thought this might be useful info, if you haven't made your choice yet.

 

[Deleted member 131795]

glad you are happy with your system. i've decided that weather comp is over-hyped. not saying it doesn't do anything, it's just diminished returns; your savings are going to be because it's a modern condensing boiler with low flow temps. the weather comp doesn't do much in addition to that, and i assume the EPH controller is on/off mode as it can't work in opentherm mode at the same time as weather comp.

i am going with a main eco compact 25kw and eph cp4 control. i think that'll get me 95% of the way there.

have you thought about what would happen to your bills if you turned it off at night?

 

[bobbyt]

glad you are happy with your system. i've decided that weather comp is over-hyped. not saying it doesn't do anything, it's just diminished returns; your savings are going to be because it's a modern condensing boiler with low flow temps. the weather comp doesn't do much in addition to that, and i assume the EPH controller is on/off mode as it can't work in opentherm mode at the same time as weather comp.

i am going with a main eco compact 25kw and eph cp4 control. i think that'll get me 95% of the way there.

have you thought about what would happen to your bills if you turned it off at night?

Hi, ok thats good then, it didn't come on last night, my night setting was 18 deg, so obviously it wasn't required, overnight temps outside were 11 deg. during the day it used about 28kwh and the house felt really comfortable. It'll be a bit of a learning curve according to weather, can always alter the weather comp curve to suit if required. Yes you are correct, EPH is just an on/off switch.

I have done a lot of research on weather comp, and I think it will be really efficient at making the house feel comfortable at the same temperature, we are home all day most days as we are retired, so it suits our lifestyle. My house is also well insulated with the max thickness of loft insulation, and the recommendation is to keep the CH on to maintain the temperature, and to enable the system to heat the house up quicker in the morning, as if the temp is allowed to go too low, with the low flow temps (yesterday 40-43 deg), it will take longer to get back to 20 deg, which is what I have selected on the boiler. Anyway, as long as we are both happy

 

[Desktop987456]

Hi, ok thats good then, it didn't come on last night, my night setting was 18 deg, so obviously it wasn't required, overnight temps outside were 11 deg. during the day it used about 28kwh and the house felt really comfortable. It'll be a bit of a learning curve according to weather, can always alter the weather comp curve to suit if required. Yes you are correct, EPH is just an on/off switch.

@bobbyt - Didn't want to hijack someone else's post (PM me if you can) but could you please let me know the heating load (how many rads) you are running on CH with 28kwh per day consumption? That's really low, I am interested to know and compare it to my system which is also Viessmann Vitdodens 100-w heat only boiler. I am not in UK though.

 

[Knappers]

It's difficult to advise without seeing the system and getting a good idea of what you want.

It's a good idea to future-proof but it could be done in different stages. Just make sure that whatever your putting in is up to future spec.

Most boilers aren't setup for HW priority (with dual flow temps) and its a fairly niche install.
I think Intergas, ideal & Vaillant have options tho.
(I've just completed one with a Worcester 4000 but I can't reccomend it as not technically allowed).

I think the point that was being made before is that your probably better off with a good reliable local engineer than with (what some may consider) an over complicated installation.

I guess the question is how much do you want to spend?

Yes a system boiler with a high gain (dual coil) UV HW cylinder, resized rads for 50°C flow temps, HW priority and load/weather compensation would be ideal (also zoning/smart TRVs may be an option)!
But they can also all be done independently without any issue...

Regarding pressurising your system, I think your best taking advice from your engineer but it would have to be a particularly ropey system for it to be an issue. As said the pressures aren't very high.

glad you are happy with your system. i've decided that weather comp is over-hyped. not saying it doesn't do anything, it's just diminished returns; your savings are going to be because it's a modern condensing boiler with low flow temps. the weather comp doesn't do much in addition to that, and i assume the EPH controller is on/off mode as it can't work in opentherm mode at the same time as weather comp.

i am going with a main eco compact 25kw and eph cp4 control. i think that'll get me 95% of the way there.

have you thought about what would happen to your bills if you turned it off at night?

Over-hyped!
Manufacturers have been hyping online control and WiFi with little emphasis on weather comp.
The only 'hype' I see is from old guys like me and other experienced engineers.
Domestic market is probably 30 years behind commercial with regards to weather comp - its hardly a new fad!
I stand by my opinion that altho literature will only state 1-2% efficiency gains, the added comfort would actually allow the economy-minded consumer to drop their temp atleast 1deg and maintain the same or better comfort level.
Then your looking at 10-15% saving.
It's one of the few truly usefull advancements in any of the modern controls (IMO)