Discuss Calculator recommendations???? in the Plumbing Jobs | The Job-board area at PlumbersForums.net
http://www.domestic-gas.co.uk/documents/CE54.pdfBack to Rileys original question. Would you not be better just doing a quick full house heat loss calc?
Just what I was always told and what I now work to mate.8kW for any cylinder up to 200l Sounds excessive IMO.
My own boiler is only 8kW and will heat the cylinder from cold for around 20 minutes and then starts cycling. In practice, we tend to reheat cylinders before they are stone cold, so I can't see a cylinder accepting 8kW very often.
I've been told all sorts of things, including that if you have a 22mm pipe from the hot outlet of a combi, then you'll have reduced flow to the bathroom because 'the water slows down when it hits the 22mm pipe'.Just what I was always told and what I now work to mate.
8kW for any cylinder up to 200l Sounds excessive IMO.
My own boiler is only 8kW and will heat the cylinder from cold for around 20 minutes and then starts cycling. In practice, we tend to reheat cylinders before they are stone cold, so I can't see a cylinder accepting 8kW very often.
Off the top of my head about 5 or 6Sorry, I read 8kW for up to 200l. What would you allow for a standard 117l cylinder then? <8kW, presumably?
If you did that you would have 8kw more capacity for the HW generation but why? especially if you think about what is going to happen to the boiler during the summer (& for that matter the spring & autumn) when there is no (or reduced heat load) the boiler is then going to be oversized. I know in this case the cylinder coil could probably take the 13.5 but buying a larger boiler than the max heat load makes no sense.I've been told all sorts of things, including that if you have a 22mm pipe from the hot outlet of a combi, then you'll have reduced flow to the bathroom because 'the water slows down when it hits the 22mm pipe'.
Hence why I need to understand everything and why I question things.
In a 2 bedroom house with 5.5kW heat losses at design temperature, you'd specify a system boiler capable of providing 13.5kW at whatever flow and return temperatures you have decided on? Is that right?
No, vented.Unvented cylinder?
No, vented.
I quote my own system because it's the only one I've had the leisure to observe in more detail than is probably healthy. My boiler can't modulate. Previous house I put a new cylinder in to run off the existing 13kW output zombie boiler. The cylinder manufacturer told me I didn't need fast recovery on a boiler that weak... and it also cycled like a mad thing once the cylinder had lost its initial chill.
I must say I'm thinking more like Chris Watkins in that I'd rather have the boiler run flat out without excessive cycling than have an oversized boiler.
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