UFH why bother when you have photovoltaics

[Donkey Table]

Hi all with the advent of photo voltaics and heat stores, low temp UFH becomes a why bother. Bags of cheap electric and hot water backed up in the heat store, just use radiators. Now Im aware radiators take up space, but consider what happens when you have to fix a UFH system. With rads at worst you unbolt and fit another. Contect the rads to a manifold best of both worlds. A themostat in every room.

With UFH faults is have a stroke time with the potential bills and disruption.

Dont start me on air source heat pumps, thats the devils vegitable. I think they are the next Enron scandal in the making.

Feel free to shoot me down.

 

[Ric2013]

The only things I can really say to disagree with you is that the output per sq m of solar thermal is greater than the output per sq m of solar photovoltaic and that some people will opt for UFH anyway regardless of what the heat source is (I run mine off a zombie boiler), and possibly the environmental input vs heat output is better for thermal system than a PV one.

We'll keep off the ASHP discussion if you like

 

[Donkey Table]

The only things I can really say to disagree with you is that the output per sq m of solar thermal is greater than the output per sq m of solar photovoltaic and that some people will opt for UFH anyway regardless of what the heat source is (I run mine off a zombie boiler), and possibly the environmental input vs heat output is better for thermal system than a PV one.

We'll keep off the ASHP discussion if you like

Thanks for that Ric.

Photo voltaic (PV) is a game changer. The panels are getting more efficient, you can add batteries, and invertors tie the system to the mains grid. This means you can suppliment your electricity demand from the heat stores using the PV or batteries and a mains invertor. If you have two heat stores, one is always being warmed by the PV during the day, I think they are even making PV 12V emmersion heaters. UFH works well with low temerature sources such as solar thermal and the devils vegitable (ASHP).

The joy of PV is you can heat your radiator system with nice and hot water on the cheap. Im doing a new build at the moment, using the SAP calculations done by the energy calcualtion company, I saved a bomb on insulation to meet current building regs. The next step is to dump the UFH liability and fit nice panel rads. I am using a manifold and 15mm speedfit to feed the downstairs, the first floor and loft room. The radiator pipe are behind the 15mm sound block plaster board, exiting at a little back box hidden behind the rads. The heat stores will also feed the gazzilion power showers the missus wants.

For those doing a room in a loft be warned there is no sound attenuation with rigid foam. What I have done is 50mm air gap, between the Proctor roof shield slate membrane, then between the raffters, 70mm rigid foam, then 100mm Rock wool sound block, the stuff in the red bags and a premier product. This is counter battened with 80mm rigid foam on the inside (yes Im aware I loose some room). House went through building regs back in 2010, so its almost 0.11 U value. The place is now silent in the loft.

The place so insulated to may need air conditioning, also fed from the PV. But thats for another day.

Oh Ive currently fitted 2Km of cat 6 network cable for all the video, cctv and network devices. The heating will be controlled by thermostats in every room and an Emerson type control system.

The Electricity board is fitting a modern domestic 3 phase incoming main now, to take advantage of the expected boom in electric vehicles and PV sharing. My neighboor says he is pushing about 14Kw in the grid every day, think how much hot water he is missing out on. The days of single phase domestic housing appears numbered.

Out has gone ASHP and no UFH. Frankly if I was a plumber I would be pushing UFH like crazy as its a job and profit creation scheme from heaven. My background is Electronics, Electrical and Software Engineering.

 

[ShaunCorbs]

You won’t be able to get 15mm in a 1g back box

you will need a 2g vertical also will need it at min 1/2 up the rads due to bends

 

[Donkey Table]

You won’t be able to get 15mm in a 1g back box

you will need a 2g vertical also will need it at min 1/2 up the rads due to bends

Yes sorry Shaun, I have use the 10mm lay flat for the radiators on the first floor and loft. I want fast heat on the ground floor, hence the 15mm pipe. Two manifolds feed the upstairs, and one will do the ground floor.

The radius of the bend of the pipe must be observed, like electric cable. The other joys is that I have used Wolf Easi joists for the first floor. Never go back to solid timber now, no creaks over large spans.

 

[ShaunCorbs]

Wouldn’t go 10mm plastic better in 10mm copper if you have to less chance of blocking

 

[Jerry]

Thanks for that Ric.

Photo voltaic (PV) is a game changer. The panels are getting more efficient, you can add batteries, and invertors tie the system to the mains grid. This means you can suppliment your electricity demand from the heat stores using the PV or batteries and a mains invertor. If you have two heat stores, one is always being warmed by the PV during the day, I think they are even making PV 12V emmersion heaters. UFH works well with low temerature sources such as solar thermal and the devils vegitable (ASHP).

The joy of PV is you can heat your radiator system with nice and hot water on the cheap. Im doing a new build at the moment, using the SAP calculations done by the energy calcualtion company, I saved a bomb on insulation to meet current building regs. The next step is to dump the UFH liability and fit nice panel rads. I am using a manifold and 15mm speedfit to feed the downstairs, the first floor and loft room. The radiator pipe are behind the 15mm sound block plaster board, exiting at a little back box hidden behind the rads. The heat stores will also feed the gazzilion power showers the missus wants.

For those doing a room in a loft be warned there is no sound attenuation with rigid foam. What I have done is 50mm air gap, between the Proctor roof shield slate membrane, then between the raffters, 70mm rigid foam, then 100mm Rock wool sound block, the stuff in the red bags and a premier product. This is counter battened with 80mm rigid foam on the inside (yes Im aware I loose some room). House went through building regs back in 2010, so its almost 0.11 U value. The place is now silent in the loft.

The place so insulated to may need air conditioning, also fed from the PV. But thats for another day.

Oh Ive currently fitted 2Km of cat 6 network cable for all the video, cctv and network devices. The heating will be controlled by thermostats in every room and an Emerson type control system.

The Electricity board is fitting a modern domestic 3 phase incoming main now, to take advantage of the expected boom in electric vehicles and PV sharing. My neighboor says he is pushing about 14Kw in the grid every day, think how much hot water he is missing out on. The days of single phase domestic housing appears numbered.

Out has gone ASHP and no UFH. Frankly if I was a plumber I would be pushing UFH like crazy as its a job and profit creation scheme from heaven. My background is Electronics, Electrical and Software Engineering.

Just did my ASHP training. Not worth it. What a load of BS

 

[king of pipes]

I can see benefits for both types of system and as you say the biggest outlay in a property is heating your hotwater , insulation is vital get that right and you need very little in KW output to heat your home, i recently fitted a Viessman boiler with weather compensation and this was a large property the construction was timber frame and well insulated when there was a outside temperature of 8-10 degrees i was using 3 KW of heat.

 

[snowhead]

There isn't a single solution that would work for every house.
P.V definitely won't work for the majority.

On a new build where the roof can be orientated to get the best gain from a panels, yes.
On a large new build with enough room for adequate sized heat stores and one that can justify having 2km of cat 6 installed,yes.
And on new builds when the insulation value can be very high, yes.

On existing terraced houses, not a chance, not enough roof surface area.
On existing Semi detatched, by default for the roof orientation a maximum ever of 50%, but likely nowhere near.

ASHP are effective but only on limited numbers of houses, high insulation value required and won't work for terraced or semi or closely built due to the noise from the outdoor units.

 

[Donkey Table]

Just did my ASHP training. Not worth it. What a load of BS

Ouch.

 

[Ric2013]

Just did my ASHP training. Not worth it. What a load of BS

The course was BS or the product is?

 

[Donkey Table]

Wouldn’t go 10mm plastic better in 10mm copper if you have to less chance of blocking

Agree with that, its my first time with plastic. Im using 15mm plastic on the ground floor.

 

[Donkey Table]

The course was BS or the product is?

One of these devils vegitables down the road, sounds like a wheat drying machine. You walk past and think what on earth is that racket. Its almost new. Especially in the cold its going like hell..

 

[Donkey Table]

There isn't a single solution that would work for every house.
P.V definitely won't work for the majority.

On a new build where the roof can be orientated to get the best gain from a panels, yes.
On a large new build with enough room for adequate sized heat stores and one that can justify having 2km of cat 6 installed,yes.
And on new builds when the insulation value can be very high, yes.

On existing terraced houses, not a chance, not enough roof surface area.
On existing Semi detatched, by default for the roof orientation a maximum ever of 50%, but likely nowhere near.

ASHP are effective but only on limited numbers of houses, high insulation value required and won't work for terraced or semi or closely built due to the noise from the outdoor units.

South facing plot Snow. 3500 sq foot, 325 sq M. The insulation is to current building regs.

 

[IND_Nick]

As above I think it all depends on the property situation as to the correct solution.
We fit a lot of UFH, especially on redevelopment stuff and it tends to be more for a comfort and space reason, rather than trying to lower anything. I also have never had any problems with UFH in over 10 years of installing it, the odd pump and mixer but nothing more than that.

PV is definitely a good idea if you can harness it for the household, especially as cars etc are heading that way. However I'm not convinced electric heating is the way forward just yet. I also tend to find that electric options are limited and once installed very few people want to service/maintain them.

I completed a Heat Pump qualification and have to agree that half way through it I realised they have very limited applications and an awful lot of excuses as to why they won't work! Plus the cost of the units is ridiculous, and that's before adaptions which will be required to make the property more efficient.

 

[Murdoch]

Problem with heating water using excess solar is that its not as efficient as by a gas boiler so it takes more energy to heat a tank of hot water up than most people realise - especially if its drained of all hot water every day

 

[Donkey Table]

Problem with heating water using excess solar is that its not as efficient as by a gas boiler so it takes more energy to heat a tank of hot water up than most people realise - especially if its drained of all hot water every day

Yes the secret is lots of insulation else your fighting a loosing battle. Have you seen the price of rigid foam at the moment?

 

[ShaunCorbs]

Problem is rigid foam isn’t suitable for cavity insulation unless it’s interlocking

 

[Donkey Table]

Problem is rigid foam isn’t suitable for cavity insulation unless it’s interlocking

I used 100mm rigid foam in the cavity. It wasnt interlocked, it was held by large plastic washer clips. This was went through the SAP calcs too. !50mm cavity. Cavity bats type, not 2400 by 1200.

 

[ShaunCorbs]

I used 100mm rigid foam in the cavity. It wasnt interlocked, it was held by large plastic washer clips. This was went through the SAP calcs too. !50mm cavity. Cavity bats type, not 2400 by 1200.

problem is as the foam shrinks your joints will start to have gaps in them with the possibility of thermal bridging

 

[Donkey Table]

problem is as the foam shrinks your joints will start to have gaps in them with the possibility of thermal bridging

Well if the foam shrinks, it will do so in flooring too. There is no UV exposure involved, and the foam recipies have improved. If shrinkage is a problem now, cavity walls are the least of our trouble. Screeds will feel it too. If I had my time again I may use a Rockwool cavity fill, only because of the sound attenuation.

 

[ShaunCorbs]

That’s why your supposed to do a min of two layers and staggered joints eg first layer left to right next layer up and down (join)

 

[Donkey Table]

That’s why your supposed to do a min of two layers and staggered joints eg first layer left to right next layer up and down (join)

No Celotex technical says single layer. Double layer of say for example 75mm to make up 150mm increase the cost greatly. The staggered joints is a common pattern, this was done with the cavity bats too. In addition if you have multiple layers of differing materials, in this case an extra two laters of foil at the 75mm middle point, you need to do a dew point calculation for the building inspector, to be on the safe side.

 

[Ric2013]

No Celotex technical says single layer. Double layer of say for example 75mm to make up 150mm increase the cost greatly. The staggered joints is a common pattern, this was done with the cavity bats too. In addition if you have multiple layers of differing materials, in this case an extra two laters of foil at the 75mm middle point, you need to do a dew point calculation for the building inspector, to be on the safe side.

A dew point calculation shouldn't be a difficult operation, surely?

That said, if foam shrinks, then I'd suggest it's not going to perform well. Not so much cold bridging as air simply convecting around it. Will know more if I ever lift a floorboard in my lounge.

 

[Donkey Table]

A dew point calculation shouldn't be a difficult operation, surely?

That said, if foam shrinks, then I'd suggest it's not going to perform well. Not so much cold bridging as air simply convecting around it. Will know more if I ever lift a floorboard in my lounge.

Yes the foil acts as a vapour control layer. However do you also silver foil tape the first layer, more cost. In which case the whole buscuit is open to any vapour in the area. I was asked for a dew point calculation for my roof insulation composite. All the beam and block foors Ive seen done used a single sheet of the required thickness.