Would like some advice on the following choice of boiler + unvented cylinder.
Vaillant 637 + vr65 / vrc430 controller
Vaillant Unistor 180L
We have a 3 bedroom house with 1 (soon to be 2) bathrooms, and 2 adults + 1 child living here. The flowrate on an open pipe is 26 litres per minute, and at a tap is 19 lpm
My thoughts for going with the 637 + 180L cylinder are to have a quick reheat time, and not store too much hot water that might sit there for ages if we don't use it. 180L seems like a good compromise, and I calculated this as follows (hope my maths isn't wrong):-
180L stored at 65 degrees + 180L cold = 360 litres blended hot water available (50:50 ratio at shower)
approx 20 litres per minute available, which means 18 mins showering before hot water depleted
Whilst hot water is depleting, reheat time for 70% of the cylinder is approx 21 mins at 37kw, which means that after 18 mins 50-60% of cylinder is hot, and another 10 mins or so of showering available
And so on
So in all, we could have continuous hot water of approx 30-35 mins at 20 litres per minute.
Does this sound right? What do you think of the 637 + 180l combo?
Cheers
Vaillant 637 + vr65 / vrc430 controller
Vaillant Unistor 180L
We have a 3 bedroom house with 1 (soon to be 2) bathrooms, and 2 adults + 1 child living here. The flowrate on an open pipe is 26 litres per minute, and at a tap is 19 lpm
My thoughts for going with the 637 + 180L cylinder are to have a quick reheat time, and not store too much hot water that might sit there for ages if we don't use it. 180L seems like a good compromise, and I calculated this as follows (hope my maths isn't wrong):-
180L stored at 65 degrees + 180L cold = 360 litres blended hot water available (50:50 ratio at shower)
approx 20 litres per minute available, which means 18 mins showering before hot water depleted
Whilst hot water is depleting, reheat time for 70% of the cylinder is approx 21 mins at 37kw, which means that after 18 mins 50-60% of cylinder is hot, and another 10 mins or so of showering available
And so on
So in all, we could have continuous hot water of approx 30-35 mins at 20 litres per minute.
Does this sound right? What do you think of the 637 + 180l combo?
Cheers