Riello Gulliver RG1 Oil Burner - I think?

swapot

Hello, newbie here. Not just to this forum, but to heating, as I come from living in the tropics.

Bought a brick/concrete house in western Greece (considered climate zone that has a Riello Gulliver RG1 light oil burner in a concrete boiler room connected to Erdecast (boiler?). It is connected to a compressor that is rusted and glass water heater and feeds 8 radiators in a 90 sqm house. Photo links below (must copy/paste into browser as I can't post live links yet).

I didn't even know what it was when I saw it.

Since the house was only used as a summer holiday house over the past five years, I don't think it has been operated since then. House has a newer 22,000 BTU air conditioner that we sparingly used as a heater to get though last winter (and dressed warm).

We have a 65 sqm unfinished ground floor that we plan to build into a one or two bedroom unit for family in the next year. I am about to purchase and install off grid solar PV that will cover energy needs for both the existing house and future ground floor unit, but since it will be off grid and batteries are expensive, I am trying to carefully plan appliances and heating. I also am more interested in becoming oil-independent, not the opposite. We live in the house full time.

So here's my question:

I am considering whether to:

1. Get rid of the oil burner and only use the air con for heat. Install a similar air con unit for AC/heat in the future ground floor unit.

2. Get the oil burner serviced and keep it for really cold spells. Add radiators to future ground floor unit.

3. Change it out for a heat pump (if the cost of a heat pump wasn't so high this would be a no brainer) and add radiators to the future ground floor unit. Can't do solar, building project, and heat pump at same time, so heat pump would have to be down the road if at all.

Could the current Riello oil burner heat an additional 5-6 radiators?

The 100 liter oil tank is about half full. Is that 5-year old oil OK to use? How long will it last? How much does it cost to use a system like this for heating?

My understanding is that oil burners/radiators are not like the AC unit - you don't just fire it up for some quick heat when it's chilly.

I would be grateful for any and all thoughts on this. Thanks!

Close-up:

hellastube.com/wp-content/uploads/2025/05/IMG_2509-rotated.jpg

Erdecast:

hellastube.com/wp-content/uploads/2025/05/IMG_2505-rotated.jpg

Boiler room

hellastube.com/wp-content/uploads/2025/05/IMG_2508-rotated.jpg

Riello RG1 label:

hellastube.com/wp-content/uploads/2025/05/IMG_2510-rotated.jpg

swapot

Not sure how the climate zone became a emoji!

Cold of winter is around 10 C (50 F), rarely gets colder than 6 C (43 F)  or hotter than 32 C (90 F) in summer. High humidity and rainy fall and winter.

QrizB

Sort @swapot but that's not a brand of boiler I've heard mentioned on this forum before.

You'll probably be OK with option 1. There are a couple of folk here who use their aircon for heat during the spring and autumn of the UK (which is a similar climate to the Greek winter, as you describe it) and they seem to get along OK.

@Martyn1981 any thoughts?