INSTALLATION:
Large house occupied only by a retired couple most of the time. Has three bathrooms, one bathroom in regular use, the others only used when visitors come.
New boiler being installed, 35Kw combi. Cold mains pressure between 3 and 4 bar, with flow rate of 20 lpm through 32mm MDPE mains connection (probably open pipe tested). Combi not expected to supply all hot water requirements when visitors present, so horizontal unvented cylinder will be added shortly in loft. Cold inlet pressure to cylinder expected to be around 2 bar. Installer is gas safe and G3 registered, well respected and reliable small firm.
WHATS PROPOSED:
Plumber would like to connect all hot water outlets to both combi and unvented cylinder to cater for situation where all bathrooms are in use. Would fit shut off valve and switch to unvented cold inlet to be closed when no visitors present. Householders would be expected to open valve and set switch to “on” a day or so before visitors came, to allow cylinder to reach temperature (legionnaires etc.).
A non-return valve would be fitted to the combi boiler’s hot water outlet, but probably not to the unvented cylinder’s hot outlet, as any back pressure would be limited by the check valve within the combination valve.
ALTERNATIVE:
The alternative would clearly be to use the cylinder to feed only the two “visitor” bathrooms, and have no connection with the combi’s hot water side. However the layout of the house, and possible changes in owners habits make this less attractive.
I WOULD BE GRATEFUL FOR:
1. Your thoughts on the practicality of scheme generally.
2. Any concrete reasons why it can’t / shouldn’t be done at all.
3. Thoughts on alternative approaches.
4. Suggestions of additional controls / safety measures.
I’m asking because the plumber and I have discussed it. Despite his having mentored me in the past I’m not convinced the approach is right, although I cannot see anything obviously wrong with it. The householders are friends of mine.
Large house occupied only by a retired couple most of the time. Has three bathrooms, one bathroom in regular use, the others only used when visitors come.
New boiler being installed, 35Kw combi. Cold mains pressure between 3 and 4 bar, with flow rate of 20 lpm through 32mm MDPE mains connection (probably open pipe tested). Combi not expected to supply all hot water requirements when visitors present, so horizontal unvented cylinder will be added shortly in loft. Cold inlet pressure to cylinder expected to be around 2 bar. Installer is gas safe and G3 registered, well respected and reliable small firm.
WHATS PROPOSED:
Plumber would like to connect all hot water outlets to both combi and unvented cylinder to cater for situation where all bathrooms are in use. Would fit shut off valve and switch to unvented cold inlet to be closed when no visitors present. Householders would be expected to open valve and set switch to “on” a day or so before visitors came, to allow cylinder to reach temperature (legionnaires etc.).
A non-return valve would be fitted to the combi boiler’s hot water outlet, but probably not to the unvented cylinder’s hot outlet, as any back pressure would be limited by the check valve within the combination valve.
ALTERNATIVE:
The alternative would clearly be to use the cylinder to feed only the two “visitor” bathrooms, and have no connection with the combi’s hot water side. However the layout of the house, and possible changes in owners habits make this less attractive.
I WOULD BE GRATEFUL FOR:
1. Your thoughts on the practicality of scheme generally.
2. Any concrete reasons why it can’t / shouldn’t be done at all.
3. Thoughts on alternative approaches.
4. Suggestions of additional controls / safety measures.
I’m asking because the plumber and I have discussed it. Despite his having mentored me in the past I’m not convinced the approach is right, although I cannot see anything obviously wrong with it. The householders are friends of mine.
