I know very little about Nest, Hive etc. Be interested to hear how you get on.
New Boiler Requirement
- Thread starter tech749
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I will update after I speak to the plumber to arrange another visit. Basically you just control everything on an app, or via the room stat, so no physical controller, uses a Hub and Receiver instead.
Got this back today, after I asked Veissmann about the boiler I wanted to use. I will see what the plumber says too.
Your Installer will need to wire the Y plan valve so there is no mid position (Hot Water priority) and you can then add the Weather Compensation accessory
| ZK07124 | Weather Comp Kit incl Control Box | B1GA |
| ZK06130 | WiFi Modem including cable |
Third party room controls (240 v switching) are still supported under Weather Compensation, these act as the timer and the Boiler then compensates the heating output from the Outdoor Sensor info and Heat Curve selection on the Boiler or Via the ViCare App
Kind Regards
Viessmann Technical Support
When they say "Your Installer will need to wire the Y plan valve so there is no mid position" I trust they they will provide a wiring diagram, as the installer may struggle to work it out for himself!
I appreciate you're going down a different route now, but to get back to the programmer, Danfoss confirm that the 975 is no longer available. They do a TPOne-M, which for some reason has volt-free on the CH side, but not the HW. That would still be suitable, as volt-free is not needed on HW for the Vitodens data sheet.
I contacted Viessmann but I'm not expecting much joy.
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I think they do, but I will check with the plumber first.
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The boiler needed extra pipework for PDHW because that's how the boiler is designed. I'd have thought it far simpler to put an OpenTherm system boiler in, keep all existing pipework and swap the Y plan for S plan using EPH OT controls to achieve PDHW.
Here's an update for anyone interested. I had a Viessmann 050 25kw combi with weather compensation, and an EPH controller connected Open Therm fitted by a local company, glad I went with them, good communication and got the job done. Original installer never got back to me with a quote after I decided to have combi fitted. Really good customer service, and I'm pleased with the outcome. There was minimal disruption, fitted in a day and a half.
New boiler just on hot water is averaging 2.5kwh per day usage as opposed to 10.5 kwh (4 kwh on pilot light alone!), on previous old system, well pleased. Hoping there'll be good savings when heating is turned on as well. Thanks everyone for your inputs.
New boiler just on hot water is averaging 2.5kwh per day usage as opposed to 10.5 kwh (4 kwh on pilot light alone!), on previous old system, well pleased. Hoping there'll be good savings when heating is turned on as well. Thanks everyone for your inputs.
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That's very economical. You recorded 10.5kwh per day in winters or summers? Could you share cylinder capacity for 1.5 hours of heating hot water daily in old system?
Hi,
It's 10.5 kwh in summer not sure about the tank capacity, it was one of the old standard copper cylinders that went in the airing cupboard, it was fully insulated with the red lagging jacket. Not sure in winter, as heating was on at same time, looked at my usage app, but it doesn't distinguish between heat and hot water obviously. Should imagine more, as water would be colder? Hot water was on from 08.00-09.00 and 1515-1545, heating on 0800-1000 and 1500-2100 using approx 55 kwh per day with those timings. Only had new system for about 2 weeks now.
It's 10.5 kwh in summer not sure about the tank capacity, it was one of the old standard copper cylinders that went in the airing cupboard, it was fully insulated with the red lagging jacket. Not sure in winter, as heating was on at same time, looked at my usage app, but it doesn't distinguish between heat and hot water obviously. Should imagine more, as water would be colder? Hot water was on from 08.00-09.00 and 1515-1545, heating on 0800-1000 and 1500-2100 using approx 55 kwh per day with those timings. Only had new system for about 2 weeks now.
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Many Thanks. That's pretty good average considering usage of 9 hours (including HW). With new boiler your usage should be well below 50kwh!
Just seen this thread your first guy was making a straight forward job that was crying out for a combi very very complicated christ knows why and anyone who measures water pressure at a garden tap especially a b an q diy one is a fool
Yeah couldn't understand the logic behind all that. I used an independant company called the Heating hub to recommend sizing and type of boiler, and they came back with Viessmann system boiler, not sure why, as I had already told them my hot water usage details, and a recommended installer for it. He didn't seem too happy that I didn't want the upheaval of new piping, and a new hot water tank, which was another extra expense. Never came back to me anyway after I said I'd rather a combi, which he did a survey for, then hasn't bothered since. Another installer said a combi would be fine, so went with them. All's well that ends well 
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