merlyn

The engineers putting in the ducts 40+ years ago insulated them. Warming the attic not a good plan much better it goes to bathroom. I'd renew the old insulation as I am of sound mind. The air is exhausted into the room whether hot or cold. Unlikely to be cold air into the bathroom though. Absolutely, heating the hall and leaving the doors open is a very strange.

We have a 40+ year old warm air system already, a gas one. We are considering blanking off the upstairs ducting from the rest of the house and heating a plenum chamber with an A2A heat pump like the Daikin Ducted – Mini Sky Air R32 for instance. https://aircon-online.co.uk/product/ducted-mini-sky-air/ The current chamber has ducts off it for 2 bedrooms and study and bathroom already. The bedrooms are unheated throughout the winter (electric blankets to the rescue) The study and the bathroom are used at the different times so a modest unit can be fitted. The ducts room inlets have physical valves to open and close when they are needed. Very '70s tech. In summer the bedrooms get very warm and sticky so units will be operating overnight in air con mode. The lounge will have its own indoor unit and the gas heating will provide the hot water for now, otherwise it will be turned off. I couldn't help noticing that I could make your life really awkward by suggesting you could heat at least all the house from one indoor unit in the attic and another in your sun house. Fascinating Thread so far. Thank you

The house is a late 70s detached in the South West, with good insulation and 20years old double glazing. It has a B EPC. Currently it has a Vaillant boiler and a Johnson and Starley warm air unit. The hot water causes the J&S unit to turn and blow the warm air it collects from the boiler's hot water. It then it heats the house. Or doesn't if you run the boiler cooler to save energy/money. Hardly any warm air reaches the upstairs. Not that that is a big problem with electric blankets. We have solar panels (3.9 kW) from 2014 so relatively unsophisticated and a Tesla battery. The house, in winter is heated by gas and the battery is charged up on cheap overnight electricity. The house runs on just the panels and battery for 9.5 months of the year and the rest is mainly gas and a bit of electricity thrown in. 1.5kWhs are generated in December and 2.5in January. Have 15kWh altogether per day. An Electric car is charged on cheap rate too and we have about 8.5Kwhs electric for heating before it goes up to 41p a kWh but can run the gas downstairs if needed. The hot water is gas. We will probably keep the gas but steadily replace it, then use it in an emergency. Initially I will test the water on here to work out the best way to adapt the warm air heating (WAH) to an Air-to-Air heat pump. (If you are not familiar with A2A they are Air conditioning units running in reverse.) The outside unit (3 connections minimum) will be mounted on the end wall with short run to the lounge unit (2.5Kw) and one other connection has a run of 7 metres to the "warm air distribution point" in the centre of the house. see photo Plenum. This will have to be modified to accept a "Ducted" unit, unless anybody knows better. The upstairs unit will only heat 1 room at a time (bathroom/study mainly) and therefore can be relatively low powered. 2.5kW again?