I have a small house, 1 bath, 1 shower, 3 wc with solar water(300l) backed up by immersion heater on timer. The solar panels supply a cylinder with 2 coils, 1 unused.
Also an annex, 1 large bath with 2 showers and 2 wc,and 4 radiators, currently not connected, 25 meters away.

I want winter hot water in the house and better hot water to annex also with hot water to the radiators there.

I plan a largish air to water heat pump on the house for winter hot water and multiple connections to the annex.

If i put in a 2 or 3 coil cylinder in the annex with 1 heated by the house solar and 1 by the new heat pump.
Should I use the heat pump coil for the annex radiators as well or the 3rd coil instead?
any suggestions are welcome

thanks for your questions

The house is in central Portugal with daylight temperatures around 25degrees centigrade, nighttime about 15 deg
Daylight about 11 hours but
Winter daytime about 10 degrees, night about 4.

When sun is not shining, inside air temperature is about 15 degrees.

and very occasionally we have frost.



Edited 1 times.

What's your design day temperature? What's the heat loss of the annex? What type of emitters, and what's their output at whatever specific water temperature you expect? Those, and about another 50 questions should get you close to an answer.

quote; Those, and about another 50 questions should get you close to an answer.

OR a crystal ball and a medium to read it.

Basically...we know he has a house in the sun. Only during daylight hours though.

all a bit technical for me, weather info is on weatherbase.com, using the city of castello branco.
so winter average temp is about 8 degrees, day length about 10 hours in winter. Rain about 15 days a month.
So those are the days when I need heating but I would like to be non reliant on sun anyway.
I burn logs for room heating but don't have any back boilers and, even if I did they would not be convenient as too much log carrying for my wife if I'm away. The emitter question i don't understand.
I like water at about 50 degrees C and rooms to be about 20 or more. The annex bathrooms have radiators, as yet not connected just to drive away the damp.

in the northeast US, we design heating systems to raise the room temperature to 70 deg F when the outside is 0 deg F. amount of window area and square footage of outside walls as well as the amount of insulation in them all figure into the equation.
emiters is a fancy term for radiators

Because of our differences in climate, from yours to ours, we use a totally different approach to heating. The equipment would also be radically different. Heat pumps are not adequate for use in most of our country. Some of the southern states have climates closer to yours.You're going to have to rely on local knowledge when it comes to your system. Good Luck and Best Wishes