Shall I replace the current gas warm air central heating?

_Sam_

Hi all our new bungalow has a gas warm air central heating. It is rather noisy when in operation, the heating vents are in the floor and have diffusers, there is a thermostat in a dining room attached to the wall (but I can partially close diffusers I suppose if I want one room to remain cooler), it heats out the bungalow literally in minutes. It may be not as efficient as a wet system, possibly due to not having radiators that can radiate heat for longer.

We also have a very recently installed gas water heater in the loft. 

My dilemma is, would it be a good idea to replace the warm air system with a traditional boiler, radiators, water pipes underfloor? The floors are easily accessible in that there are carpets and floorboards. The floorboards are quite nice though and I wouldn't want them to be damaged in the process as some rooms we'd like to have them varnished and keep them (I'm aware of insulating concerns, another problem to solve!)

Or would it be more prudent to keep the heating as it is, until the new ASHP systems come down in price and possibly become more advanced? (One plumber told us to stay clear from ASHP as they are not good at heating and offer no cost savings for the user).

chrisw

If it's working fine and you're reasonably happy that it does the job, I would leave it until it breaks down and needs replacing and then consider installing radiators, etc.

Section62

_Sam_ said:

Or would it be more prudent to keep the heating as it is, until the new ASHP systems come down in price and possibly become more advanced?

That's what I would do.  If the current system works and meets your needs there is no sense in changing it whilst the future of domestic energy is in a state of flux.

The plumber's advice might be true today (I couldn't say either way myself), but it could be completely wrong next month.

_Sam_

The heating does appear to work fine, noise might be a bit annoying but nothing I couldn't live with for now. A bit concerned about dust in those 70 years old underfloor ducts but was thinking to research maybe some filters, and we have an air purifier that should help too.

benson1980

I thought gas warm air systems in general were quite efficient? The principles sound quite appealing versus wet central heating pipes everywhere I have to say...

I would personally hold fire. We have done similar recently in terms of upgrading part of our heating/hot water system (out of some necessity due to poor hot water pressure upstairs, and very small capacity cylinder- gravity fed) and when we had three heating engineers round to quote, we asked them about future proofing the bits that were being upgraded.

Two of them just told us it will always be gas, and potentially hydrogen and therefore just to focus any upgrades on gas compatibility. There has to be a possibility as you say that ASHPs will become more viable, cheaper to run etc. The prospect of hydrogen has been subject of a number of independent reports regarding viability, or lack of, but they didn't know any of this. For me anyway, they seemed a bit stuck in their ways, and insistent that things will remain the same- I guess why wouldn't they this is what they have been working with. The third chap we had knew all about the pros and cons and at least seemed much more progressive and up to speed with developments, and introduced some future proofing ideas. Therefore I'd take what your plumber says with a pinch of salt. That may be the case now, but not in the future. Personally there's no way I'd be looking at a slightly unnecessary overhaul of a gas central heating system presently.

Bendy_House

Hi Sam.

Do you know how much of a void there is under your floor - is the a gap you can look down? Or, where is the DPC on the outside relative to ground level?

Old floors look great where cleaned up, but with the future of fuel costs, you'd be nuts to consider having bare floors 'unless' you can get under them to (a) fully draught-proof them, and (b) insulate them. 

The Octopus guy reckons they are going to get the price of ASHPs down to 'gas boiler' level soon - they are starting a new factory in, I think, N.I. That could be the time to explore that change. However, it 'will' require a well-insulated property to be effective.

I think, since it's currently working fine, I'd personally hold off until then. A wet (radiator) system working off an ASHP will also require 'oversized' rads, so best wait until you know how well insulated you can make your home, and size the rads accordingly.

Perhaps spend some time researching; most effective (cost & disruption) ways of adding insulation, best types of rads to fit (even look at 'skirting board's types), other ways to supplement the heating (solar & PV etc), and not jump too soon?

And also research the heating you have, and how to control it - it sounds mighty powerful!

sandy700

I replaced my warm air heating with radiators in 2016 and my gas consumption has went from 24,000 kWh a year in 1991 to 12,000 kWh in the past year though I have had new double glazing and increased the insulation in my home.

I'm also saving the £300 plus BG would be wanting to maintain and service the warm air system compared to a service once a year.

I think I will start to save money in another 5 years.
As has been said wait until it needs replacing, the reason I replaced mine was BG "suggesting" I needed more ventilation which caused an almighty draught in my kitchen and cause the temperature there to drop drastically during the night when the heating was off.
Plus it was 25 years old and noisy

Bendy_House

sandy700 said:

I replaced my warm air heating with radiators in 2016 and my gas consumption has went from 24,000 kWh a year in 1991 to 12,000 kWh in the past year though I have had new double glazing and increased the insulation in my home.

I'm also saving the £300 plus BG would be wanting to maintain and service the warm air system compared to a service once a year.

I think I will start to save money in another 5 years.
As has been said wait until it needs replacing, the reason I replaced mine was BG "suggesting" I needed more ventilation which caused an almighty draught in my kitchen and cause the temperature there to drop drastically during the night when the heating was off.
Plus it was 25 years old and noisy

And the moral of that story would appear to be, don't listen to BG.

DG, on the other hand, sounds good :-)

_Sam_

BG is British Gas? Interesting that they charged so much for servicing, when we bought this bungalow among the documents the owners left was a note from a local heating company who serviced the warm air heater last year and they charged £95 for this. I assumed this would be a once-in-a-year procedure, but will double check with the heater's instructions. 

Our heater is Johnson & Starley Economaire 65, it is pretty old but still in production it seems. The bungalow has good loft insulation and cavity insulation according to the EPC.

I had a look and found one gap in one of the vents near ducting, it was 60cm down quite a drop. But the bungalow is on the hill and looking from the outside the DPC height ranges from 15cm to 68cm. When looking around the duct I saw something that very much looked like loft insulation, yellow stuff, right underneath the floorboards. But it is clearly not everywhere because just on the other side of the vent I could drop the tape measure right down.

There was a really good draft from the little gap I peeked in (once the diffuser is back it covers it and draft disappears), but I didn't seem to notice much draft from the gaps in between the floorboards. 

_Sam_

That’s how the vent looks without diffuser, and bottom right tiny gap is where I peeked in

Bendy_House

Good chance there's an accessible void under there to carry out proper insulating when the time comes and you expose the floor. Until then, I wouldn't trust it.

You don't have to 'feel' a draught from a specific area; it's usually more of a general perculating, but that's enough to leach much of the heat away.

The house we're in had a stupidly-expensive small garden room fitted on it when we moved in, that the vendors were inordinately proud of. It had no opening windows(!), and ASHP heating and cooling, which operated through floor vents like yours. You could both hear the fan and feel the air flow - hellish. You could also feel a draught when it wasn't running, so clearly it leaked like a sieve. We never used it. I ripped it out at the first opportunity. What I found - as I crawled around on my back in the 2' void under the floor - was that the insulation down there consisted of 2" of badly-fitted polystyrene held in place with battens. It was next to useless, full of gaps, and not even tight against the flooring, so a nice air flow even above it. Just carp. Rubbish. Useless.

So, if you want to expose your lovely floor, I'd suggest a good investigation of what's going on underneath. I honestly suspect that most attempts at insulation is hugely flawed, as gaps are left which allow draughts that will largely erase any benefits.

Ditto for external wall insulation. How the hell can that work effectively if there's a draughty cavity in between?

That's why - to me- the best method by far is to line the insides.

Rant over :-)