Still researching the options for a boiler swap and big change to DHW production. One plausible looking option is the Vaillant ecoTEC plus range of system boilers. Combined with their digital weather compensation box of tricks it would appear to do most things including allowing split temperature operation.
Anyone got one, fitted one, serviced one etc care to comment on their experiences. The tech spec looks good, as does the construction etc, but how doe the rest of the ownership equation stack up?
Just got one, due to be fitted next week. Ecotec 618, VR65, VRC430 and external temperature sensor. I recommend Vaillant to most people who ask me; I was leaning towards a Viessmann but the gas fitter recommended Vaillant and parts are probably easier to get. Pipework and fittings were easy, field wiring to VR65 & VRC430 is low voltage (except that to the 2 x 2-port zone valves). I think there is another box of electronics that is used with an additional mixing valve set to give two modulating temperature zones. I believe the heating goes to a high temperature if there is a simultaneous heating and DHW demand. Ask me next week. Or next month when I've worked out the controls.
Yup, I had a look at those as well. I could not see a way of doing two independent heating zones (in addition to DHW) on those though.
I was looking at the VRC430. with an additional VR81 in a second rad zone. A VR61 to interface to 3 x two port valves.
I think the VR61 can drive a three port mixing valve to that effect. Not sure I really need quite that level of sophistication (although it would be well suited to driving a rad zone and a UFH one) - I would be happy with one weather compensated set temperature for both rad zones, but with independent prog stat control on both.
fig 4.4 in:-
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I believe the heating goes to a high temperature if there is a
Yup I expect you are right - there is only one flow and return from the boiler[1].The trick would be to schedule the cylinder heating at a time when the heating is in setback mode, and hence unlikely to fire.
[1] I noted that some like the system version of the Worcester 30CDi you install an additional diversion valve in the boiler to provide a dedicated DHW heating feed and return as far as I can tell.
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