Affordable heating option for new SAP regs.

[Gavin]

Hi All,

 

I'm currently planning my first new build property. Money is extremely tight and I'm trying to keep my budget below £100k. I'm looking for suggestions on the best option on heating at the most cost effective option. Air pumps, LPG, oil, solar panels are all floating around but I'm not sure which is best.

 

Suggestions would be helpful!

 

Gavin

[PeterW]

None .....

 

Invest  in the the fabric of the building and make it far exceed the regs on insulation and air tightness and you shouldn't need heating.

 

UFH coils in the floor can be done for less than £100 at build time and no need to add the manifold unless you need to. 

 

If you go conventional and have gas available then it's seen as the default cheapest, but @SteamyTea has some good info on direct electric heating 

[ProDave]

What size of house? To get under £100K is doing well, I doubt I will achieve that in spite of me doing so much of the work myself.

 

As Peter says, No 1 is insulate, insulate, insulate. No 2 is air tightness. No 3 is good doors and windows, No 4 is an MVHR unit (mechanical ventilation with heat recovery)

 

Then you can think about heating, which should not be much.  I am going for an air source heat pump and to buy one for self install should be under £1500, possibly under £1000, i.e not a great deal more than an ordinary boiler.

 

I personally would not have oil or LPG again, the price is too volatile. (though I will have LPG for cooking, the usage is so low that the cost hardly matters)

 

I will be fitting solar PV, but by the time I get there, I doubt the (already low) feed in tariff will exist any more. So that means a DIY installed system bought as cheap as possible, and almost certainly some form of battery storage to ensure near 100% self usage.

 

Tell us more about your house design and where you are building.

 

Oh and welcome to the forum.
 

[Declan52]

Where is your build???

How big is your build??

What shape is it??

What do you intend to build it from??

What's the ground conditions like??

How close are the services, gas electric sewer???

What building skills knowledge have you got???

These will have a big say on your final cost. 

I built a 220sqm bungalow in Ni and except plumbing electrics and plastering I done the rest myself and I have spent approx £106,000 and I still have the driveway to do.

[SteamyTea]

Hard to say what is best without some detail.

But I think that for water heating on a budget either inline heater or E7 and a relatively small cylinder (all depends on occupancy).

 

As for the fabric, it is hard to separate insulation and airtightness.  The two work/don't work in conjunction with each other.

You can get away with less insulation if you have good airtightness 'after' the insulation i.e. airtight layer on the outside.

But, if you have really good airtightness, then you really need to fit MVHR, which puts the price up.

 

Ideally, you want good windows, good floor and ceiling/roof and reasonable walls, it depends of the relative areas where you spend the money.  Then design the place to make fitting MVHR easy.

Then a small ASHP for the space heating .  It could be Air to Air or Air to Water and underfloor heating.

If Air to Water, it can be combined with a Sunamp and get some pre heat from the buffer tank.

Then PV into the Sunamp.

Roof integrated can be cheaper than 'normal' on the roof.

 

The main thing is to look for bargains now and buy them up, even if they are not needed for a year or two.

[Gavin]

Thanks for the info Gents, very helpful.

 

1. Where is your build??? Scotland

 

2. How big is your build?? 1.5 storey (total floor space 132m2)

 

3. What shape is it?? Standard shape with dormer roof

 

4. What do you intend to build it from?? Timber frame and brick / render

 

5. What's the ground conditions like?? Good ground

 

6. How close are the services, gas electric sewer??? Serivecs on street and sewer placed on site. Previous owner spent £15k getting services to site

 

7. What building skills knowledge have you got??? I'm a Civil Engineer so mostly roads, bridges, arena / building but no experience of houses

 

I'm hesitant to buy a cheap ASHP if the technolgy is not that tried and tested. I don't want to risk it not working. I'll get in touch with my Architect again and see what his thoughts are.

 

Thanks again all!

 

[ProDave]

Which part of Scotland?

 

Is this a plot you have bought or a knock down and rebuild?
 

[nod]

7 hours ago, Gavin said:

Hi All,

 

I'm currently planning my first new build property. Money is extremely tight and I'm trying to keep my budget below £100k. I'm looking for suggestions on the best option on heating at the most cost effective option. Air pumps, LPG, oil, solar panels are all floating around but I'm not sure which is best.

 

Suggestions would be helpful!

 

Gavin

wow Ive just started mine I will do two thirds of the work myself Perhaps more

I have 200k budget and 50 contingency  Even at this early stage I expect

to use most of  that

[Ferdinand]

Need to be careful comparing like for like here, but £100k should be vaguely possible for a build budget - even possible including your plot sometimes. Some plots are free or nearly free. 

 

That 132sqm size, though :-)

 

A couple of years ago there was the excellent £100k house series.

 

Ferdinand

Edited November 20, 2016 by Ferdinand

[ProDave]

6 hours ago, Ferdinand said:

 
 

A couple of years ago there was the excellent £100k house series.

 
 

And some of them only got "built" for £100K because they were not finished.
 

[Declan52]

It's not impossible to do what you want but some where along the line you will have to compromise on materials or labour or even both. 

You will need to plan everything to the last detail as every penny counts and will need to be good at haggling to get the best deal. like Dave says most of them houses where not finished as they just ran out of money so be prepared to live in a half finished house if needs must.

Put the money into the things you can't change like the structure and when more money gets freed up then you can change tiles floors kitchen units etc. 

Have you done any calculations to find out what your heat demand will be.

[joe90]

Re your point of a cheap ASHP, mine was cheap but very proven technology as it's made by carrier of the states, the biggest manufacturer ( as far as I am aware), just cheap because the company who badged it decided to exit that particular market.

[gravelld]

You've said what you're building but not why?

 

What do you want out of the house?

 

Your first two replies were spot on.

[jack]

1 hour ago, joe90 said:

as it's made by Carrier of the states, the biggest manufacturer ( as far as I am aware)

 

As an aside, I believe Panasonic manufactures more air-conditioning & heat pump compressors than any other company in the world.  I don't know how that translates into completed units - I assume they manufacture for others as well.

 

But the general point is spot on: heat pumps are one of the best understood pieces of tech around.  It's the same tech that's in every consumer fridge and aircon unit, and they are, in general, incredibly reliable.  The important thing is to make sure that it isn't being asked to do more (or too much less) than it's designed for.  In general, the bad reports from air source heat pumps installations have been in leaky, poorly insulated buildings where they just weren't the right answer.  

 

Build it insulated and airtight, and ASHPs are fine.

 

You also need to think about whether your heating and hot water will be supplied by the same system.

[joe90]

Regarding splitting the heating from DHW, I don't know enough about the controls and proDave on another thread has the same basic idea of providing both in his build like me but I wonder if you can deliver one temp to UFH and another to a hot water tank?

[MikeSharp01]

5 minutes ago, joe90 said:

I wonder if you can deliver one temp to UFH and another to a hot water tank?

This is possible because the UFH will (can) mix return water from the UFH with hot water from boiler to control slab temperature the full hot water can go off round the hot water tank.

[jack]

Mine's set up to do DHW between 5 and 6:30 am every morning.  Temp for that is set at 55 deg.

 

It then runs the UFH for several hours during the middle of the day (the most likely time it'll be able to use the PV) as required.  This is set for the lowest possible temp of 25 deg - I wish it would go a little lower!  There's a bit of weather compensation (max temp of about 28 degrees if it's below zero outside), but frankly I suspect weather compensation in the short-term sense is a bit pointless in a well-insulated house.

 

I suppose you could run the UFH at the same time as the DHW and allow the TMV on the manifold to mix the temp down, but in my case there's no need to have them both going at once.  I also don't like the idea of generating high grade heat at lower efficiency, and then mixing it down to a much lower temp.

[joe90]

2 hours ago, jack said:

 I also don't like the idea of generating high grade heat at lower efficiency, and then mixing it down to a much lower temp.

This was my point about setting different temps for the ASHP delivering to two different needs.

[jack]

34 minutes ago, joe90 said:

This was my point about setting different temps for the ASHP delivering to two different needs.

 

Yep, my reply was directed at this comment from Mike, which as I interpret it suggests the possibility of mixing high temp water to a lower temperature for use in UFH: 

4 hours ago, MikeSharp01 said:

This is possible because the UFH will (can) mix return water from the UFH with hot water from boiler to control slab temperature the full hot water can go off round the hot water tank.

 

My bog standard Panasonic controller allows different temps to be set for heating and DHW modes.  I seem to recall Jeremy's offered that option as well.

 

Worth checking with the manufacturer you're using (or thinking of using), but certainly it doesn't appear to be an uncommon feature.

[joe90]

Thanks jack, my controller is in storage on site, next time I am down I will dig it out and have a look ?

[MikeSharp01]

28 minutes ago, jack said:

Yep, my reply was directed at this comment from Mike, which as I interpret it suggests the possibility of mixing high temp water to a lower temperature for use in UFH: 

Yes that is what I meant but its only mixing down with the return flow from the UFH and the other high grade losses will only be in the pipework between the heat source and the UFH mixer valve. However your point about high grade heat, what is your definition of high grade I wonder, and mixing is a good one and perhaps we (I) need to think about it in energy terms more directly. My thinking was that the boiler would only deliver what was required, modulate down and stay within its efficiency range, once the hot tank was filled.  Trouble is, when you expect that, the efficient modulation range of the boiler (or other heat source) I think the smallest boiler goes down to about 3Kw which I suspect is much more than you would need to put into an already warm slab which is surrounded by an airtight and well insulated structure. Your other point about getting the floor temp down is a very good one that needs thinking about, as you say I also seem to recall JSH struggling with that one as well but I have not followed it up. Is the limit set by the mixer valve I wonder. Off I go to read the JSH stuff again.

[Stones]

2 hours ago, jack said:

My bog standard Panasonic controller allows different temps to be set for heating and DHW modes.  I seem to recall Jeremy's offered that option as well.

 

Worth checking with the manufacturer you're using (or thinking of using), but certainly it doesn't appear to be an uncommon feature.

 

The Nibe we had in our last house had that ability.  As you say, I think it's pretty standard function.

 

The difficulty we found with storing DHW at a lower temperature than traditional systems, is that you run out when using the shower because of the differential required for the thermostatic valve to work.  We had IIRC 210 litre capacity but this was only just enough for two showers.  However, whilst there may not have been enough DHW for showers, there would still always be plenty of water left over 38C but under 48C available for sinks / basins.  To get round this, we have opted to go with a 300 litre cylinder.  

 

We don't intend heating DHW to more than 50C using our ASHP.  I'm more than confident that the heat pump will be able to cope with this, albeit at a slighty reduced COP.  Having number crunched, I don't think there is much (if anything) cost wise if we were to go the other route and simply preheat with a heat pump and top up with immersion / inline heater as a matter of routine.  We will have a fortnightly legionella cycle via immersion top up.  

[jack]

I wish I could determine what impact the waste water heat recovery system has.  No doubt it makes difference, but I don't know whether it's like an effective 20L or 100L of hot water.

[MikeSharp01]

31 minutes ago, jack said:

I wish I could determine what impact the waste water heat recovery system has.  No doubt it makes difference, but I don't know whether it's like an effective 20L or 100L of hot water.

What system are you using for this, should be possible to get an idea shouldn't it, amount of water x temp delta x efficiency of the system or have I missed something, only looked at such systems in the first stage, have kept the waste water separate from the 'number 1s & 2s' to the plant room in case it looks like a worthwhile proposition. (Must add that to my post above about things to remember.)

[SteamyTea]

34 minutes ago, jack said:

I wish I could determine what impact the waste water heat recovery system has.

You can do a theoretical study.

Take some basic assumptions and scenarios and run them though Excel (it is what Solver is for).

So if you know the quantity of water going though the recovery unit, the temperature differences and the efficiency of the unit, you can get a good idea.