Combi vs tank - which should I go for?

[b21playa]

As your system is working atm I would get the water main done first as it’s lead you might be able to get a deduction from the water board

Yes I’m going to phone around tomorrow for this. Then will try and find some deals on tanks etc once I’ve worked out which one.

 

[b21playa]

Managed to find a heat loss calculator online. I’ve input all the rooms with details of sizes and windows/wall type/insulation levels and got an output of 92,000 btu or 27kw. This is for a 3-storey house with solid brick walls and some decent sized rooms.

Looking at tank specs, a coil may need 20kw itself to heat tank but guess as this isn’t all the time, don’t need to have 20kw additional from a boiler. Maybe a 30kw would do

 

[EvilDrPorkChop]

Managed to find a heat loss calculator online. I’ve input all the rooms with details of sizes and windows/wall type/insulation levels and got an output of 92,000 btu or 27kw. This is for a 3-storey house with solid brick walls and some decent sized rooms.

Looking at tank specs, a coil may need 20kw itself to heat tank but guess as this isn’t all the time, don’t need to have 20kw additional from a boiler. Maybe a 30kw would do

30kw and do HW priority.

 

[SJB060685]

As above go for a PDHW setup. Now that you have arrived at a figure of 27kw can you see the problems you would experience if you let the engineer who recommended 37kw install one that size?

 

[b21playa]

30kw and do HW priority.

Thank you. I did think 37kw was excessive. I think final question is really regarding which boiler and system or heating only.

 

[EvilDrPorkChop]

Thank you. I did think 37kw was excessive. I think final question is really regarding which boiler and system or heating only.

System.

If it was me, i'd go for the Vaillant EcoTec Plus 630. In doing so will allow you to use the Vaillant controls which will do HW priority.

You will probably want to allow for some extra expansion too with the volume of water.

37Kw would of been fine tbh, as you've got to remember they have a 1:6 (or the newer models 1:10) modulation range. It isn't running at 37kw constantly.

 

[hometech]

continuous water heater is the way forward. Then add a small combi for the heating. Would be much cheaper option at around £1200-1400 for the 2

 

[SJB060685]

I’d consider the Viessmann 200 system boiler and controls. 17-1 modulation range and 19-1 on the newer models I believe, full stainless steel hex and advanced weather compensation as standard.

 

[b21playa]

System.

If it was me, i'd go for the Vaillant EcoTec Plus 630. In doing so will allow you to use the Vaillant controls which will do HW priority.

You will probably want to allow for some extra expansion too with the volume of water.

37Kw would of been fine tbh, as you've got to remember they have a 1:6 (or the newer models 1:10) modulation range. It isn't running at 37kw constantly.

So even if I got a good enough deal on a new 637 that would be fine? In terms of extra expansion do you mean by an additional expansion vessel?

The 637 was actually recommended to me by the first installer I had over, he said it would suit whole needs.

Would the valiant controls work with any cylinder and how would that affect the current 3 channel Drayton wiser system I have .

Many thanks

 

[b21playa]

I’d consider the Viessmann 200 system boiler and controls. 17-1 modulation range and 19-1 on the newer models I believe, full stainless steel hex and advanced weather compensation as standard.

Are these more efficient with greater modulation? Guessing price wise they are all around the £1500 mark. Tank wise I was suggest a tempest or gledhill 250L