Rob1992

I’m not sure to be honest, I don’t know what it’s doing for the four or so hours it takes for the house to warm. The flow pipe to manifold is generally scolding and the return pipe from the manifold mainly luke warm

Can I ask why you say that and why do heat pumps have a procedure weekly to heat the cylinders up for a brief period?

Hi, 1st post! We completed our self build a year ago and I have been trying to find the most economical way of running our heating and DHW system but can't seem to find a conclusive answer, so hoping someone here may be able to help. The set up we have is as follows: Basement - UFH: barely required Ground floor - UFH: main heating source of house. Blend valve set at 30 degrees 1st and 2nd floors - rads: barely required Gas boiler- 30KW Intergas RF Cylinder - Kingspan Ultrasteel 300L MVHR system The boiler is currently set to fire at 75 degrees to get the cylinder to 60/65 for legionella, but this seems a huge overkill when the UFH is blended to 30 degrees and the cylinder not needing to get above 50deg (?). Other info, the boiler normally fires for about 4hrs a day in the morning to get the ground floor to temperature and but then needs no more until the next day. This normally raises the temperature a couple of degrees. The timer for the cylinder is set to come on once a day. I am thinking it could be more economical to lower the boiler temperature to 55 degrees, and maybe run an immersion programme once a week (?) to get the cylinder to 65. I really don't know the sweet spot at which a boiler is most economical so hoping someone can give me some honest science! Many thanks in advance.