Hello!
My old gledhill gulfstream 2000 is on its last legs, and I think it's time to replace it. On the whole I've been happy with the system because it is all self contained in one cupboard and I had mains pressure DHW on demand and all was good with the world. The heating output of the gledhill is 29kw.
Since it seems these sorts of thermal store units are out of fashion, my choices are between a larger combi or system boiler.
It's a 4 bedroom, 3 storey house with 2 occupants and about 15 rads. We are very used to high pressure hot water so I think the combi route, while cheaper and maybe more efficient is a risk.
I am leaning towards a Vaillant system due to the good reputation and would be looking at an Ecotec Plus System either 630 or 637 paired with a unistor cylinder of some capacity.
I have a few questions for you guys!
- have I been too quick to discount a combi?
- would the 30kw output of the Vaillant 630 be sufficient assuming the 29kw of the gledhill was absolutely fine? Not sure if having a separate boiler and cylinder incurs losses! Any advantage going for the 637?
- how do I choose the capacity of the unvented cylinder?
- would I need an extra expansion vessel? According to the manual I have read the internal 10l one is good for up to 100l total system volume. Does the unistor cylinder become part of that system volume? I know in my current system the 70l thermal store is very much a part of the radiator system and shares the same water. Is this the case in a traditional sealed system?
- my radiator piping is microbore, 10mm I think. Would this be ok?
I do plan on getting this all done professionally but I would like to know enough beforehand to specify the important parts of the design!
Cheers
My old gledhill gulfstream 2000 is on its last legs, and I think it's time to replace it. On the whole I've been happy with the system because it is all self contained in one cupboard and I had mains pressure DHW on demand and all was good with the world. The heating output of the gledhill is 29kw.
Since it seems these sorts of thermal store units are out of fashion, my choices are between a larger combi or system boiler.
It's a 4 bedroom, 3 storey house with 2 occupants and about 15 rads. We are very used to high pressure hot water so I think the combi route, while cheaper and maybe more efficient is a risk.
I am leaning towards a Vaillant system due to the good reputation and would be looking at an Ecotec Plus System either 630 or 637 paired with a unistor cylinder of some capacity.
I have a few questions for you guys!
- have I been too quick to discount a combi?
- would the 30kw output of the Vaillant 630 be sufficient assuming the 29kw of the gledhill was absolutely fine? Not sure if having a separate boiler and cylinder incurs losses! Any advantage going for the 637?
- how do I choose the capacity of the unvented cylinder?
- would I need an extra expansion vessel? According to the manual I have read the internal 10l one is good for up to 100l total system volume. Does the unistor cylinder become part of that system volume? I know in my current system the 70l thermal store is very much a part of the radiator system and shares the same water. Is this the case in a traditional sealed system?
- my radiator piping is microbore, 10mm I think. Would this be ok?
I do plan on getting this all done professionally but I would like to know enough beforehand to specify the important parts of the design!
Cheers