Boiler swap. INTEC 40GS to Worcester Greenstar 32CDi Compact Combi

[TonyS]

Dear Forum members,

Hope that you are all doing well!

• We are thinking of moving our existing boiler from its cupboard to a bathroom corner to free up some space
• A local specialist has recommended that we install a smaller boiler, so that it fits into the bathroom nicely

My goal is to ensure that the proposed replacement (Worcester Greenstar 32CDi Compact Combi) will perform adequately when replacing the existing boiler (INTEC 40GS), which is 5 years old, had a diverter valve replacement, and is on warranty (annual plan).

House
Semi-detached, new-build (I would say - well insulated), 2-bedroom, two-story
9 radiators, two showers and a bath

Boiler comparison

Range:	Greenstar CDi Compact	InTec
Brand:	Worcester Bosch	Alpha
Flow Rate:	11 L/min	18.4 L/min @ 30°C, 15.8 L/min @ 35°C
KW:	32	40
Model Number:	32CDi LPG	40GS
Rated Heat Output (Prated or Psup):	24 (Prated)	28
Water Heating Energy Efficiency %:	89.8	90
Water Heating Declared Load Profile:	XL	XL
Seasonal Space Heating Energy Efficiency %:	94, A/94%	92
Water Heating Energy Efficiency Class:	A	Alpha
Sound Power Level (Indoors):	52
Seasonal Space Heating Energy Efficiency Class:	A	Alpha
Depth (mm):	280	360

Could we get away with the new CDi Compact? Or should we stick with the objectively more powerful 40GS?
I would be very grateful if you could share your experience!

Thank you in advance!

 

[Scott_D]

I think you will struggle to find someone prepared to move your existing boiler.
I’m not a fan of Worcester but is the 36kw version an option?

 

[gmartine]

I don't think the flow rate you quote for the WB 32CDi is correct, I had a quick look at a couple of sources that state it should be 13.1 l/m and the 36 CDi is around 15 l/m.

As Scott suggests I don't know why the company are quoting for the less powerful WB boiler as they are the same physical size except to keep the price down. You already have a really good flow rate (if you get it) you'll miss it but as you say maintaining performance is key.

If you haven't done it, it's a crude method but just measure how long it currently takes to fill a 1 litre container and do the maths and see what the true HW flow rate is before you go chasing it. As it's a new build chances are you have the requisite water and gas pressure and flow rates that allow your current boiler to work at it's optimum but that isn't always the case.

My instinct is to say that will be quite an outlay for a bit more cupboard space and replace a perfectly reliable boiler so have you exhausted all your options in that regard? Without meaning to be condesending perhaps an innovative chipie could redesign or incorporate same additional or hidden cupboard space somewhere.

 

[king of pipes]

The heating would be ok but you will struggle with the hot water delivery showers need a minimum of 8 litres a minute for a decent shower, even if your fit flow restrictors you will struggle to run two hot water outlets at the same time. Kop

 

[gmartine]

Duh more coffee required, well spotted I didn't see that two showers were in use and obviously that's why such powerful boiler was put in. Easy decision for me then, keep your current system and find some space elsewhere.

 

[TonyS]

I think you will struggle to find someone prepared to move your existing boiler.
I’m not a fan of Worcester but is the 36kw version an option?

Hi Scott,

I think the 32 kW option was suggested because of its size:

It would fit into a 30cm cupboard.

 

[TonyS]

I don't think the flow rate you quote for the WB 32CDi is correct, I had a quick look at a couple of sources that state it should be 13.1 l/m and the 36 CDi is around 15 l/m.

Thank you for highlighting this. I took the values from here Worcester Bosch Greenstar CDi Compact 32CDi NG combi boiler | Wolseley - https://www.wolseley.co.uk/product/worcester-greenstar-32cdi-combi-boiler-only/ but it must be wrong. I wish I could edit my original post to correct the mistake.

As Scott suggests I don't know why the company are quoting for the less powerful WB boiler as they are the same physical size except to keep the price down. You already have a really good flow rate (if you get it) you'll miss it but as you say maintaining performance is key.

I think they are quoting for it because of the space. Please see my response to Scott above. We are trying to free up the space to install an additional set of stairs into the loft and have some unused space in the bathroom.

If you haven't done it, it's a crude method but just measure how long it currently takes to fill a 1 litre container and do the maths and see what the true HW flow rate is before you go chasing it. As it's a new build chances are you have the requisite water and gas pressure and flow rates that allow your current boiler to work at it's optimum but that isn't always the case.

I see! So the actual flow rates can be less than what the current boiler could deliver.. I will check that, thank you!

My instinct is to say that will be quite an outlay for a bit more cupboard space and replace a perfectly reliable boiler so have you exhausted all your options in that regard? Without meaning to be condesending perhaps an innovative chipie could redesign or incorporate same additional or hidden cupboard space somewhere.

It is a great idea and I now see why it is not a great idea to touch an existing boiler.. The boiler move is to free up space for that set of stairs to the loft, but perhaps the chippie could design an appropriate set of stairs! Will investigate. Thanks again!

 

[TonyS]

The heating would be ok but you will struggle with the hot water delivery showers need a minimum of 8 litres a minute for a decent shower, even if your fit flow restrictors you will struggle to run two hot water outlets at the same time. Kop

This is very useful information, thank you!

 

[TonyS]

I don't think the flow rate you quote for the WB 32CDi is correct, I had a quick look at a couple of sources that state it should be 13.1 l/m and the 36 CDi is around 15 l/m.

I have found some values on the official website:

 

[TonyS]

I’m not a fan of Worcester but is the 36kw version an option?

Actually, just spotted that 36 kW option is the same size! That's at least one thing we could do to get a better flow, thank you for suggesting this!