Installing a vented hot water cylinder downstairs

moslo

I've a vented HWC upstairs but I want to install a second one downstairs to supply a bathroom for 2 downstairs bedrooms (extension). At the moment I'm using the upstairs HWC for all bathrooms and it doesn't provide enough hot water at peak times.

I can't fit a bigger HWC upstairs, I don't want to fit an electric shower or an unvented water heater, so I'm looking at a vented direct HWC downstairs. I'm hoping to plumb the HWC into the existing HW and CW pipes for the downstairs bathroom.

My question is; how do I vent the downstairs HWC? The most obvious would seem to be to run a pipe from the HWC to the top of the storage cistern in the attic but it's a difficult route and about 8 metres.
There is a possible alternative, through the extension roof and up the gable end to a level above the cistern but the HW would just be vented outside rather than into the cistern; is that even possible?

whizbang

Is there room in extension roof for an additional storage tank ?

Would make sense to have separate supplies if you have separate hot water system.

John.G

moslo wrote: »

I've a vented HWC upstairs but I want to install a second one downstairs to supply a bathroom for 2 downstairs bedrooms (extension). At the moment I'm using the upstairs HWC for all bathrooms and it doesn't provide enough hot water at peak times.

I can't fit a bigger HWC upstairs, I don't want to fit an electric shower or an unvented water heater, so I'm looking at a vented direct HWC downstairs. I'm hoping to plumb the HWC into the existing HW and CW pipes for the downstairs bathroom.

My question is; how do I vent the downstairs HWC? The most obvious would seem to be to run a pipe from the HWC to the top of the storage cistern in the attic but it's a difficult route and about 8 metres.
There is a possible alternative, through the extension roof and up the gable end to a level above the cistern but the HW would just be vented outside rather than into the cistern; is that even possible?

Apart from vent installation difficulties you may find that a combined system will not give consistent hot water temperatures as depending on the draw off point one HWC may supply more water (and then colder) than the other. If you are happy with the upstairs hot water pressure then as suggested above, you may consider installing a CWST at the same height above the new cylinder as the existing CWST is above the existing cylinder and completely split the two systems.

moslo

whizbang wrote: »

Is there room in extension roof for an additional storage tank ?

Would make sense to have separate supplies if you have separate hot water system.

That's not a bad option. There's certainly room in the extension 'attic' for a storage tank and having a bit more water storage in the house could be useful, especially if the extension ever becomes self-contained.

moslo

John.G wrote: »

Apart from vent installation difficulties you may find that a combined system will not give consistent hot water temperatures as depending on the draw off point one HWC may supply more water (and then colder) than the other. If you are happy with the upstairs hot water pressure then as suggested above, you may consider installing a CWST at the same height above the new cylinder as the existing CWST is above the existing cylinder and completely split the two systems.

The upstairs water pressure is fine, in fact, if it were higher then the hot water would get used up quicker as people tend to shower for a fixed time irrespective of the water flow. As mentioned to whizbang, there is a mini attic in the the extension where I could fit a low profile CWST. I just need to price the tank and accessories but at least I wouldn't have to drill a large hole through the house wall and lift floor boards to route the vent pipe.