Powering underfloor heating using a pellet boiler stove

[Mocame]

I am renovating a small (60 sq m) building to provide a home for a relative who has a low income and I need to install the most cost efficient heating system possible.

The renovation won't qualify for SEAI grants (because the building wasn't previously occupied as a residence) and as a result the cost of installing a heat pump is prohibitive for us. Instead we are thinking of installing a pellet boiler stove (one of the small ones that looks like a wood burning stove) and using it to power underfloor heating or perhaps radiators.

Has anyone got any experience of using this heating system? How did you find it? Are there any pitfalls I should be aware of?

 

[Leo]

Do you have planning permission for those works? If you are concerned about heating costs, you should be concerned about the local authority coming in and forcing you to undo all the work.

 

[Zenith63]

Cannot answer your question about pellet burners and UFH sorry, but have you considered an air-to-air heatpump? I'd be amazed if you can install underfloor heating and a pellet burner cheaper than an A2A system. There was a thread about them recently - https://www.askaboutmoney.com/threads/air-to-air-heat-pumps-in-ireland.232195/

Just to give you an idea, you might get away with something like two of these at €700each - https://www.buyitdirect.ie/p/lg-s12...it-smart-air-conditioner-with-heat-pump-s12et. You need to get them installed of course, but I still think they'd come in a lot cheaper than pellet burner/UFH and will be cheaper/easier to run and provide cooling in the summer if required.

This is assuming you're going to insulate and airtight the place to a half decent level, but I assume you are if you're talking about new floors (UFH).

 

[Mocame]

Thanks for the reply Zenith63. I will have to dig up the existing slab which is not level and not insulated so I reckon that I may as well put in underfloor heating when installing a new insulated slab. I also think that having no radiators works well in a small space because it doesn't restrict furniture placement, In addition, I plan to replace the single glazed windows with triple glazing, insulate the roof and the walls with insulated plaster board. So the building should be quite well insulated on completion.

 

[Wandering_Dazed]

UFCH wet systems need a constant heat source and take time to heat up the screed/floor to the desired temp. That would mean feeding wood pellets into the stove constantly over several hours to get things up to temp. From a quick googling it is possible to plumb in a wood stove to complement air pumps/fossil boilers but that requires a thermal store which isn't going to work in your situation.

The renovation won't qualify for SEAI grants (because the building wasn't previously occupied as a residence) and as a result the cost of installing a heat pump is prohibitive for us.

Does the property qualify for the vacant property grant?

Vacant Property Refurbishment Grant

The Vacant Property Refurbishment Grant provides funding so you can refurbish vacant properties to live in or rent out.

www.citizensinformation.ie

I will have to dig up the existing slab which is not level and not insulated so I reckon that I may as well put in underfloor heating when installing a new insulated slab.

IF you go for underfloor heating make sure it is installed correctly and pressure tested fully before the screed is laid. Most UFCH issues are caused by incorrect installation from the outset. (Namely pressure testing before screeding, flooring installation and other professionals sticking screws or nails through the pipes)

As someone who has just purchased an older house which is UFCH throughout...the amount of times I've had to tell people about the UFCH is unbelievable! Let alone how the system hasn't been looked after....but that is another story.

Good luck!

 

[Zenith63]

Thanks for the reply Zenith63. I will have to dig up the existing slab which is not level and not insulated so I reckon that I may as well put in underfloor heating when installing a new insulated slab. I also think that having no radiators works well in a small space because it doesn't restrict furniture placement, In addition, I plan to replace the single glazed windows with triple glazing, insulate the roof and the walls with insulated plaster board. So the building should be quite well insulated on completion.

I'm a big fan of UFH, added it to a few rooms we were renovating and wish I could do more. Great way to heat rooms and as you say radiators take up space and heat unevenly. But we had to have a water based heating system to cover existing radiators in all other rooms.

If I was doing a small house from scratch as you are I don't think I'd bother with all the complexity of water based. If you use anything other than a heatpump you'll have to put in a mixing valve/pump because the boiler will not be able to supply water cold enough to the UFH, expansion vessels, buffer tanks (if going heatpump) and a huge amount of 'stuff' to pay for and look after in future. I don't know how many rooms are in this place, but if it's a small number then a couple of minisplits (aka A2A heatpumps) seems like a much more elegant solution. Take the money saved on plumbing and use it to maximise airtightness, you'll end up with a very comfortable setup.

 

[Mocame]

Do you have planning permission for those works? If you are concerned about heating costs, you should be concerned about the local authority coming in and forcing you to undo all the work.

why would I undertake building works without planning permission?

 

[Mocame]

I'm a big fan of UFH, added it to a few rooms we were renovating and wish I could do more. Great way to heat rooms and as you say radiators take up space and heat unevenly. But we had to have a water based heating system to cover existing radiators in all other rooms.

If I was doing a small house from scratch as you are I don't think I'd bother with all the complexity of water based. If you use anything other than a heatpump you'll have to put in a mixing valve/pump because the boiler will not be able to supply water cold enough to the UFH, expansion vessels, buffer tanks (if going heatpump) and a huge amount of 'stuff' to pay for and look after in future. I don't know how many rooms are in this place, but if it's a small number then a couple of minisplits (aka A2A heatpumps) seems like a much more elegant solution. Take the money saved on plumbing and use it to maximise airtightness, you'll end up with a very comfortable setup.

thanks very much for this excellent advice. I have looked into the option of an air to air heat pump and this does look like a viable option. I received a quote of €7,695 (inc vat) to supply and fit the heatpump, three internal heaters and a hot water boiler. This is an affordable solution for us and along with solar panels and good insulation should make the place very easy to heat.

 

[Leo]

why would I undertake building works without planning permission?

You'd be surprised how many do and how many of those are forced to rip it all out again later. Just looking to make sure you avoided that trap. Whoever is certifying compliance should be a good source of advice on elements like this as you'll need to factor heat source into ensuring you meet current energy performance requirements.