My head is wrecked, need advice - OFCH heating & rads upgrade to underfloor Air to Water?

sudo911

Ok so really need some help and guidance here guys.

Just purchased a new house. It was built in 2007 of a timber frame construction with double-glazing and an OFCH heating system (not condenser) and solid stove in main living room. It has a B3 rating. It seems to heat up ok, but not hold the heat for long.

I'm looking to get this house as comfortable as possible heat-wise, and lessen the cost in which to do so. Given we are effectively gutting the house and the missus wants to put tiles on the whole bottom floor, an underfloor heating system appeals greatly.

Here are the two options I'm thinking

1) upgrade the OFCH boiler with a new condenser-type system. I'm going to have to replace a good few of the rads anyway as we are taking down some partition walls etc. We would look to put in Solar for heating the water for when we would not be using the oil (summer months etc) and maybe keep an insert wood pellet stove in the main living room.

2) do away with all the rads downstairs and put in an underfloor heating system. We were concerned about the costs of ripping up the floors but came across this company that effectively cuts the tracks for the underfloro piping out with a specialized machine. To drive the system we were thinking of going an air-to-water system. For the blast of heat in the winter months, we may still keep the insert wood pellet stove in the main living room.

I should also state that I am going to have all of the external/internal walls slabbed with 50mm drywall insulation. I'm also going to replace the existing doors with composite versions. The previous owner did put in a lot of extra insulation in the roof that he said made a world of difference. I've also been told of a new type of wall ventilation vent that uses a sensor to automatically open/close to let enough ventilation into the room to avoid the older white plastic vents.

I love the idea of the underfloor heating system, even with the extra cost of the installation.

I'm NOT keen on the extra electricity costs to drive the air-to-water heat pump. I've heard lots of people talk about problems with these systems and the high electricity costs of running these. I've heard you can run these underfloor heating systems using a condenser oil burner - but I'm guessing that is much less efficient and its going to end up costing me more to run than the air-to-water. Is putting in a solar system for electricity to take the bite out of the air-to-water costs an option or even feasible?

The problem I have is that everyone has a different opinion and I'm no wiser as to what is the best solution for our needs. I'm hoping you guys can give me suite pointers or guidance here.

antoinolachtnai

I think you need proper advice given how much money you are going to spend on this project

A lot depends on what the actual heat loss is. If it really doesn’t keep heat, I would consider external insulation. Internal insulation, you could do that sure, but only if you have proper written sign-off from your professional advisers (internal insulation can bring its own problems). Internal insulation is also disruptive. Are you really gutting a 15 year old house? It sounds like what you are really doing is remodeling and redecorating.

you could put in a heat pump, sure. Is it a good idea? Requires a detailed study.

Furze99

https://www.boards.ie/discussion/comment/119893236#Comment_119893236

That was my first thought - this house is only built 2007. Doesn't say much for our building regulations and standards if it needs this much work. A B3 rating is pretty good, if it's true. These ratings though are based as much on the regulations in force at time of construction and not necessarily how well they were applied, as it's not practical to open up walls and floors to examine detailing. If the house has a chimney, that will limit the rating as well afaik. These A rated houses built now are supposed to be very airtight and definitely no chimneys.

Surely it should be well enough insulated. I'd investigate what's there first if it was mine, both what's in the walls and roof. Maybe there are draughts that could be addressed.

On the economics - the cost of heating oil will rise & fall. So you could calculate over say 10 years what the potential increase and costs will be and compare that to the upgrade costs of installing underfloor. As to how you fuel the system, I've only ever seen electricity prices rise over time. Maybe the promised green land will arrive sometime and the cost of electricity will fall. Maybe.

MicktheMan

https://www.boards.ie/discussion/comment/119893236#Comment_119893236

It is a timber frame house so external insulation is out.

MicktheMan

Op, if your house heat up reasonably quick but also loses the heat quickly then this is likely not an insulation issue but rather an air leakage issue.

Before considering anything further such as adding insulated slabs etc, I would advise having the house tested for air tightness (heat loss survey). The result of this should inform you on how best to proceed. From my experience, anything else is really only guesswork resulting in likely expensive mistakes.

Wearb

Timber frame houses have a a very low thermal mass compared to a block house and this loss might be normal. The upside of a low thermal mass is that it will have a faster heat up time.

893bet

https://www.boards.ie/discussion/comment/119898218#Comment_119898218

This is really it.

Look at Airtightness first. What would a full Airtightness survey cost? Maybe 500 up to 1k?

All I know is any of those air to water or heat pumps in a non airtight house will mean it’s on the whole time and you are gonna have a serious bill every two months.

MicktheMan

https://www.boards.ie/discussion/comment/119898362#Comment_119898362

Correct, and to add to this, because of the lack of thermal mass you are more dependent on air tightness to keep warm and therefore good air tightness in a TF house is a must.