Help me choose a Worcester Bosch combi boiler

Dedekind

Hello,

as part of our renovations we are now in a position to choose the boiler. This is a 3 bedroom house with 1 bathroom + 1 toilet downstairs, 6 radiators + tower rail, and underfloor heating in the kitchen (about 20 square meters).

We will do a loft conversion in the future adding possibly 1 or 2 radiators and 1 bathroom.

We are decided to go with a combi boiler, and one of the Worcester Bosch Greenstar range. It can be either 30kw or 35kw.

The difference is that the 35kw only comes in the slightly more expensive 8000 range, whereas 30kw comes in the 4000 range.

Shall I be safe and go with 35kw? From what I've seen it looks like 30-32 should be ok but I don't want to end up having to change my mind in the future. I am not too worried about it being too powerful, I'd rather be over than underpowered.

Let me know your thoughts, thanks!

SaverRate

have a look at BOXT as see what they recommend when you type everything in. I would 100% future proof the boiler if you planning to stay there and have the loft conversion. When we changed our boiler we allowed for an extra downstairs toilet and an upstairs shower along with a single storey extension radiators. 

BUFF

Hot water demand is likely to be your deciding/limiting feature especially if there is a chance in the future of wanting 2 showers/baths going at the same time.

Also, when specifying controls make sure that they can talk to the WB boiler's (proprietary) EMS bus & modulate/load compensate (ideally weather compensate too). Atm I think that restricts it to WB's own controls but at least they should be warrantied for the same period as the boiler.

daveyjp

Cold water flow rate will dictate whether it is necessary to spend the extra on a 35kw boiler. 

If the rate isn’t sufficient for the heating capacity don’t waste your money. 

knightstyle

We had a Worcester Bosch Greenstar 2000 installed earlier this year it is 30kw and is fine for our 4 bed house, detached with good insulation.
Just make absolutely sure in writing what warranty you will get as the advertising false, we only got a 2 year warranty as some of the cost was from a grant.
Plus check your gas pipe to the kitchen is big enough for all the appliances.
DD had a Veissmann  fitted around the same time and IMO it is a better boiler.

Bendy_House

Dedekind said:

Hello,

as part of our renovations we are now in a position to choose the boiler. This is a 3 bedroom house with 1 bathroom + 1 toilet downstairs, 6 radiators + tower rail, and underfloor heating in the kitchen (about 20 square meters).

We will do a loft conversion in the future adding possibly 1 or 2 radiators and 1 bathroom.

We are decided to go with a combi boiler, and one of the Worcester Bosch Greenstar range. It can be either 30kw or 35kw.

The difference is that the 35kw only comes in the slightly more expensive 8000 range, whereas 30kw comes in the 4000 range.

Shall I be safe and go with 35kw? From what I've seen it looks like 30-32 should be ok but I don't want to end up having to change my mind in the future. I am not too worried about it being too powerful, I'd rather be over than underpowered.

Let me know your thoughts, thanks!

Both will be fine with your CH, as they can modulate down to cope with a low demand. You may wish to check each one's specs, tho', just to make sure what the min CH output is - I guess you want this to be around 5kW or a little above.

Assuming both are fine, then I'd personally go 35kW. I fitted a 30kW GlowWorm in our 3-bed house, and whilst it gives a cracking shower, I sometimes felt I'd like it to have a little in reserve.

Neither will supply 2 showers at the same time, but assuming your cold water flow rate and pressure is very good, the 35kW will be a little less affected by other taps being used.

With thermostatic showers, the worse you'll suffer from either is a temp drop in flow, but less detrimental effect from the more powerful boiler.

What else does the 8000 have over the 4000? 'Opentherm' or other sophisticated boiler control? If so, probably worth it.

But, first check is mains flow and pressure.