Viessmann 100 11kw or Vaillant ecotec plus 610

[ILEX]

Hi,

I'm trying to make a decision on these two system boilers which seem to be the most like for like compared to others. I've read up as much as I can on the forum before posting but can't come to a conclusion. I still need my heat loss calculations done first but I'm very confident that it will be low due to the recent upgrades on insulation and size of property, which is a 3 bed detached, approx 98 sqm. No UFH. Obviously if I am wrong after calculations then I would adjust Kw but I would still like to choose between these two manufactures.

I plan to do PDHW with a 150L indirect unvented cylinder. Still unsure if I'm going weather or load compensation as I've never had experiences with either of them.

I'm trying not to base everything just on specifications between them as customer support, parts availability and how they perform in the real world are also just as or if not more important. However, I only have online information available to me, so this was my result;

Viessmann 100w - 11kw

- Modulation down to 3.2kw
- PDHW & wifi App out of the box
- Choice of my own filter/deaerator
- Additional purchases for weather/load comp, outdoor sensor or Vitorol 100-E
- Support/parts availability seem a bit lacking and expensive
- 10 yr warranty as standard, 12 yr for £270 (with approved installer)

Current price approx £788

Vaillant ecotec plus 610 - 10kw

- Modulation down to 2.8kw
- PDHW requires VR71
- Additional purchases for wifi App requires myVaillant connect box
- Additional purchases for weather/load comp, Sensocomfort/Sensohome
- Support/parts availability seem decent but also can be expensive
- 7yr warranty as standard, 10yr warranty if Vaillant advanced filter pack used (with approved installer)

Current price approx £1224

150L indirect unvented cylinder

Either OSO DC or Vaillant Unistor


Clearly you get a lot more with the 100w for less and it definitely starts to get real pricey with the ecotec and it's additional extras. As stated earlier, I'm aware there are other factors to consider but this is obviously a one time, long time purchase so I'd rather just be happy during that period.

As for the cylinder, I wasn't sure if I should consider getting a heat pump variant. At this point it all became a bit overwhelming. Would it be 150L for 2/3 people but the ASHP equivalent is 180/210L? If so, are the costs of storing an extra 50L ish being and also being reheated quicker a significant extra running cost or not so much?

Where I was getting confused is with PDHW you get the benefit of quicker reheat times, so with an ASHP variant and basic logic, is that even faster?

I know there are many posts on which boiler to get, so I do appreciate that you had the patience to read another one. Thanks.

 

[desktop987456]

Pros in the forum would be interested in
- existing Pipework;
- rads sizes; double or single panel
- existing or prior HW arrangement in the property
- which boiler did you have in the property and were there any issues
- are you upgrading the heating system or just the boiler etc.

 

[Flembot]

@ILEX How did you get on with this in the end?

 

[ILEX]

@ILEX How did you get on with this in the end?

So my heat loss was around 4.5kw. With it being that low it made more sense to get the 200w 11kw to get better modulation, condensing etc. The price is obviously more, almost double and you still have to facture in the extended warranty which can be up to £480 for 12 years (however viessmann don't force you to install a filter/deaerator, some others do in order to gain extended warranty) but I figured it's going to be in for a long time and again, the low heat loss.

With that decision I opted for the OSO DC 150L (the non heat pump variant as I can't see me installing one until the 200w dies) as this should be ample with PDHW. I say should be, because I've only just ordered this and it'll be installed soon. I don't know if that helps you at all?