Installing hot water radiators in a detached garage

Hi. Have you considered thermostatically controlled oil filled electric radiators? Bob.

Things to consider: Before a boiler is installed a number of issues has to considered, how the building was constructed roof type does it have insulation or not, external walls single or cavity what type of construction and insulation, windows single or double glazed = to work out the diameter of each room size this will determine what "U" value for each room calculate all "U" values that converts into BTU,s this will then dictate what boiler size you require. This a website that explains all. https://great-home.co.uk/radiator-sizing-guide-and-btu-calculator/ I would recommend getting a qualified plumber or electrician, to work out the best solution that would work in a most cost effective way that keeps you up to date with new technology and innovations that could save you money long term.

Yes it is possible, but the suggestion of thermostatically controlled oil filled electric radiators with a timer is a good idea as installing will be cheaper, assuming there is power already in the garage. If you still wanted to extend your heating from your house I would want to zone the garage which would mean.. Tapping into the heating, 22mm pipe to insure good flow. Installing an additional 2 port valve, so you can control it independently with it's own programmer and stat. Getting cables back to boiler or wiring centre. Running heating feeds out of the building. Digging a trench to run the pipes in and lagging them, backfill the trench. Then get pipes into the garage to desired locations. With electric rads you simply hang them and get power to them, but interrupt the power with a programmer so you can control when they come on. Hope that helps

Tho there is nothing wrong with the answer by the previous plumber, if you want to extend the system and change the use of your garage I'm sure it is possible to extend the central heating if you want to go down that route. There are many online calculators for working this out. If your house is a new build it may have a combination boiler which have outputs designed to provide instant hot water to bathrooms and the load of the central heating is less than the output required to instantly heat your hot tap water. so i'm sure it would be ok to extend the heating system. The online calculators take into account the types of wall floor and ceiling insulation, so if your really wanted central heating in there but it was not enough then you would have a great many options with insulation that would reduce the load required by the room on the boiler. Make sure to fit TRVs to the radiators so that in winter you can turn off the heating in the gym whilst your family remain warm in the rest of the house. another way to to do this would be to make a separate zone with a zone valve but perhaps more hassle than worthwhile (especially since there are now automatically controlled TRVs which have their own thermostats which are wireless and can be put in the garage. so no lifting floorboards or running wires etc it could be that the previous plumbers suggestion of oil filled electric heaters is more practical. I would use several online calculation sites to get an average but i would go bigger rather than smaller or just on target as radiators are pretty cheap really and can always be turned down with the TRVs but if they are too small cannot be made to produce any more heat. hope this helps

yes easy to do and yes it will put more load on the boiler.