Glad I was sat down!!

[SteamyTea]

53 minutes ago, JamesPa said:

One might argue that it's the same problem that Ofsted has

That crossed my mind.

But was thinking more about how the school/college/university staff view it.

Edited May 6 by SteamyTea

[JohnMo]

19 hours ago, MikeSharp01 said:

Although it is what it is, the EPC system, but doesn't that make a laughing stock of the whole EPC panjandrum.

Not sure about that, although @TerryE has the skill set to set and manage direct heating to be cost effective, many people don't. The next owner could just change to a standard tariff, switch the heating on and then have to live with the cost. Which is going to 4x the cost of gas or ASHP.

 

The EPC system is just a comparison tool, flawed but ok in most cases

[MikeSharp01]

13 minutes ago, JohnMo said:

not many people don't

Did you mean 'do' rather than 'don't'?

[TerryE]

27 minutes ago, JohnMo said:

The next owner could just change to a standard tariff, switch the heating on and then have to live with the cost. Which is going to 4x the cost of gas or ASHP.

 

First, since we have absolutely no intent of selling in the near future, this isn't really an issue for me. 

 

Next, I have a real issue with talking about monthly run rate as if it is the absolue goal.  Surely we should be talking about LCoH from a consumption perspective.  Our house is passive-class and has high thermal inertia.  If some putative new owner simply switched to a timer based E7 tariff then the house would still be for more cosy than most new houses and it would still be very hard to make a proper payback case for installing and ASHP.

 

Many members also seem to assert that using your ASHP for DWH is a must.  Why?  As I said in an earlier post on this topic we spend about £150 p.a. on water heating.  Why go to all the hassle of extra buffer tanks, dual level ASHP control, dropping the overall CoP by maybe 20% just to save £100 a year (or even 3× that if we used a lot more HW): you have more kit to install, to have an annual maintenance contract and to discount the extra installation costs over the expected equipment life?  The numbers just don't add up for us.  Sorry.

 

The SAP calc should not penalise any form of renewable heating solution.  It should penalise fossil based heating solutions.  Our's is not a typical mass build; it a passive-class house designed and built to a high spec.  Actual performance is what should count in this scenario.

Edited May 6 by TerryE

[JohnMo]

52 minutes ago, TerryE said:

First, since we have absolutely no intent of selling in the near future, this isn't really an issue for me. 

But the EPC cannot take this fact into account. As I said it a comparison tool nothing more nothing less.

 

52 minutes ago, TerryE said:

we spend about £150 p.a. on water heating

By using a time of use tariff and smart control. A more typical 8 kWh of hot water on E7 could be closer to £3-400 per year at 14p per kWh.

 

Not really much additional kit to have an unvented cylinder heat pump heated, if buying either cylinder new, £100 uplift in cost compared to immersion only and it may (mine did) come with a 3 port diverter. Connect diverter to heat pump and temperature probe to cylinder - you are heating via ASHP. No buffer or additional control required.

 

 

[JamesPa]

10 hours ago, TerryE said:

Many members also seem to assert that using your ASHP for DWH is a must.  Why? 

It's a requirement for the BUS grant.  If you aren't taking the grant then you are right in some cases, mine included, that the payback time vs just using an immersion heater can be rather long and the money might well be better spent elsewhere.  This is particularly the case if you already have a functioning dhw system that the 'industry' insists on replacing.

[BotusBuild]

Ooooh, we're nearly back on topic with mention of the BUS grant 🙂 

[Nickfromwales]

18 hours ago, MikeSharp01 said:

Did you mean 'do' rather than 'don't'?

It’s OK Mike, I’ll edit it lol 🫡 🙄😉

[TerryE]

9 hours ago, JamesPa said:

It's a requirement for the BUS grant. 

 

Thanks.  I've just checked BUS Property owner guidance, version 3 and you are right: to be eligible the ASHP must provide both space and water heating.  The ASHP model and the installer must also be MCS certified.  That's the big stumbling block for me. 

 

As I said in an earlier post I've already made our house "ASHP ready" during the build about 7 years ago.  I really only need a small, say 3-5 kW unit with output flow at ~30°C driving direct into our warmslab or via a PHE.  About the same amount of work that @JohnMo described above for adding DHW support.  Maybe £3-4K work and bought-ins, if I did this myself and depending on what ASHP deal I could source. Entirely fit for purpose and just about achieving my 10 year payback constraint, but this would not achieve MCS certification and therefore this approach would not comply with Planning / Building Regs, so a no-no as far as I am concerned.

 

The MCS installers that I talked to wouldn't touch this approach or some variant thereof with a barge pole.  They'd want to rip our entire system our and based on the size of our 3 storey detached house, replace it with standard template based on something like a 11 kW ASHP, buffer tank, new UVC, etc. at maybe £15⁺K (OK,  less BUS grant); all to save me maybe £400 p.a.  Crazy.

 

Edited May 7 by TerryE

[JamesPa]

1 hour ago, TerryE said:

 

Thanks.  I've just checked BUS Property owner guidance, version 3 and you are right: to be eligible the ASHP must provide both space and water heating.  The ASHP model and the installer must also be MCS certified.  That's the big stumbling block for me. 

 

As I said in an earlier post I've already made our house "ASHP ready" during the build about 7 years ago.  I really only need a small, say 3-5 kW unit with output flow at ~30°C driving direct into our warmslab or via a PHE.  About the same amount of work that @JohnMo described above for adding DHW support.  Maybe £3-4K work and bought-ins, if I did this myself and depending on what ASHP deal I could source. Entirely fit for purpose and just about achieving my 10 year payback constraint, but this would not achieve MCS certification and therefore this approach would not comply with Planning / Building Regs, so a no-no as far as I am concerned.

 

The MCS installers that I talked to wouldn't touch this approach or some variant thereof with a barge pole.  They'd want to rip our entire system our and based on the size of our 3 storey detached house, replace it with standard template based on something like a 11 kW ASHP, buffer tank, new UVC, etc. at maybe £15⁺K (OK,  less BUS grant); all to save me maybe £400 p.a.  Crazy.

 

It's worth unpacking that.

 

BUS requires MCS and both space and water heating by ashp

 

Building regs do not require MCS or that dhw is heated by ashp

 

Planning under express consent does not require MCS unless your LPA make it a condition which is unlikely.  Under permitted development MCS is required (there is a possible argument that if you install to equivalent standards it's ok, but if you wish to deploy this I'd get a certificate of lawful development in advance because this argument is untested (and in my view shaky) and, more importantly, the burden of proof if your LPA disagree lies with you).  Either way planning doesn't require dhw by ashp

 

I'm not sure whether the MCS standard actually requires dhw to be by ashp (it's worth checking MIS 3005-d), but many MCS installers will insist anyway on ripping out whatever functional dhw you have so their rookie plumbers can fit a pre-plumbed cylinder.  However there are some that are more sensible.

 

Depending on your situation you may be able to circumvent the grant chasing vampires, but most can't.

 

And yes it's crazy but it's what you get if you don't have the necessary skills in the civil service, have politicians almost none of which have any engineering or science qualifications, and thus are entirely reliant on the industry to advise on regulation without any meaningful ability robustly to interrogate them.  Of course I'm not suggesting that is what we have!

 

 

Edited May 7 by JamesPa

[JohnMo]

If you have internal space or shed something like this.

 

https://trianco.co.uk/activair-indoor-9111-9111

 

Run at a fixed unit temperature.

 

It's mounted internally so no need for any planning or permitted development palaver. You could even hook up the exhaust side of MVHR to strip any useful heat out of that (after a bit of due diligence) in winter and take a CoP gain.

 

Leave your DHW as it is.

[MikeSharp01]

1 hour ago, TerryE said:

11 kW ASHP

At the risk of offending our fellow members - WTF.. you can actually prove, using the three riders of the MCS apocalypse viz; data, physics and algebra that you only need 3kW and that your DHW demand is manageable in that envelope so why emit the carbon making an 11Kw unit when 3 will do it. This whole game is madness but if you want a decent EPC, in your self build, then your choices / options  are limited.

[Alan Ambrose]

>>> using the three riders of the MCS apocalypse viz; data, physics and algebra

 

Very nice turn of phrase  👏 ouch!

[JamesPa]

43 minutes ago, JohnMo said:

If you have internal space or shed something like this.

 

https://trianco.co.uk/activair-indoor-9111-9111

 

Run at a fixed unit temperature.

 

It's mounted internally so no need for any planning or permitted development palaver. You could even hook up the exhaust side of MVHR to strip any useful heat out of that (after a bit of due diligence) in winter and take a CoP gain.

 

Leave your DHW as it is.

 

43 minutes ago, JohnMo said:

If you have internal space or shed something like this.

 

https://trianco.co.uk/activair-indoor-9111-9111

 

Run at a fixed unit temperature.

 

It's mounted internally so no need for any planning or permitted development palaver. You could even hook up the exhaust side of MVHR to strip any useful heat out of that (after a bit of due diligence) in winter and take a CoP gain.

 

Leave your DHW as it is.

Interesting 

 

Assuming they really are 3kW then 3 will do 9kW which is more than sufficient for most houses and gives at least a 3 to 1 turn down ratio.  It's almost tempting given my ongoing battle over planning consent.  Interesting that the auxiliary heater (if fitted) heats the incoming air, not the outgoing water.

Edited May 7 by JamesPa

[JohnMo]

21 minutes ago, JamesPa said:

 

Interesting 

 

Assuming they really are 3kW then 3 will do 9kW which is more than sufficient for most houses and gives at least a 3 to 1 turn down ratio.  It's almost tempting given my ongoing battle over planning consent.

Or do a hybrid, 3kW would do a big lump of the year, the heat pump can drive an aux heater, so you could configure to hybrid mode very easily. Just put a PHE in the heating circuit on its secondary side and a loop from another heat source on the primary side.

[JamesPa]

12 minutes ago, JohnMo said:

Or do a hybrid, 3kW would do a big lump of the year, the heat pump can drive an aux heater, so you could configure to hybrid mode very easily. Just put a PHE in the heating circuit on its secondary side and a loop from another heat source on the primary side.

I was wondering that as well.  If they did 4kW, which is my actual normal load for most of the heating season it would be very tempting indeed!

[joe90]

23 hours ago, TerryE said:

The numbers just don't add up for us.  Sorry.

Don’t apologise Terry fir thinking (and doing) outside the box and proving your point in spades (actual cost over the years) yours is a good example of simply “insulate insulate insulate (and airtightness) “ and the simplest and cheapest way to provide the little heat you need at minimum cost. (But able to change to an ASHP if required) an example to us all 👏

[G and J]

2 hours ago, JohnMo said:

If you have internal space or shed something like this.

 

https://trianco.co.uk/activair-indoor-9111-9111

 

Run at a fixed unit temperature.

 

It's mounted internally so no need for any planning or permitted development palaver. You could even hook up the exhaust side of MVHR to strip any useful heat out of that (after a bit of due diligence) in winter and take a CoP gain.

 

Leave your DHW as it is.

I’ve a horrible feeling I’m going to make myself look really dumb here, but….

We’ve just got planning permission and we are about to start serious designing/decision making with the help of our architect, (hence spending nearly every waking minute with nose pressed to this forum).  I don’t have a heat requirement figure yet.  
 

Have spoken to an MCS person who has impressed me with his common sense and the simplicity of solution he has outlined, i.e. UFH and DHW run from “small”  3 to 5kw ASHP in garden.  
 

But, if I’ve understood it I could put a unit like this literally next to the MVHR unit, and not have the unit in the garden, maybe get even better efficiency by using exhaust air, and save myself capital too.   If so why does anyone have an outside ASHP?

[joe90]

If you are talking about a monoblock ASHP they do go outside, a split unit has an outdoor bit and the gubbins (compressor) inside , the amount of air from an MVHR unit is minimal, the air requirement for an ASHP is huge, one won’t really impact on the other.

 

edit, just read your link, this is a new animal to me, a totally indoor heatpump, no mention of COP (efficiency), will interesting to see what other build hubbers  make of it.

Edited May 7 by joe90

[G and J]

40 minutes ago, joe90 said:

If you are talking about a monoblock ASHP they do go outside, a split unit has an outdoor bit and the gubbins (compressor) inside , the amount of air from an MVHR unit is minimal, the air requirement for an ASHP is huge, one won’t really impact on the other.

 

edit, just read your link, this is a new animal to me, a totally indoor heatpump, no mention of COP (efficiency), will interesting to see what other build hubbers  make of it.

I’d never heard of them till I saw JohnMo’s link.
 

Yes, now you point it out I can understand that the MVHR will (should) only deliver a low volume of air and in winter it’ll only be slightly warmer than the outside air anyway. 
 

So forgetting the MVHR link, if there’s space inside (which I have), this looks an attractive option.  Especially compared to my ‘half way down the garden mono block ASHP’ plan.  I can’t help thinking I’ve missed something here?

[JohnMo]

18 minutes ago, G and J said:

I can’t help thinking I’ve missed something here?

I would read the manual and make sure it does what you want, think it's a pretty simple heat pump 

[TerryE]

5 hours ago, JamesPa said:

Building regs do not require MCS or that DHW is heated by ASHP.  Planning under express consent does not require MCS unless your LPA make it a condition which is unlikely. ...

 

Thanks, IIRC the Planning Portal says that any ASHP installation can fall under Permitted Development if the installation complies with MCS 020 and part of this standard requires that the installation must be carried out by an MCS approved installer. Without a PD exemption, normal planning and building control applies.  This is all a lot simpler if the installation is done as part of the initial build and part of this planning and building control approval, but in our case that was over 6 years ago.

 

As a post sign-off install, this control itself introduces a shed load of bureaucracy and costs.  In the case where the proposed ASHP is to the rear and within the property curtilage, you would need to demonstrate to BControl that the installation complies with gas-safe, positioning and noise regs.   In this last case it would be practically impossible to get BC sign-off of your calcs unless the ASHP unit is an MCS approved model.

 

BTW that Trianco unit has a heat output of 3 kW and a nominal power draw of under 1 kW. 

Edited May 7 by TerryE

[joe90]

@G and J why is your heat pump position half way down the garden?

[G and J]

19 minutes ago, joe90 said:

@G and J why is your heat pump position half way down the garden?

Our plot is 24’ wide, and we’re building in pretty much the footprint of the bungalow we will be demolishing.  We’re too close to each neighbour to have an ASHP either side, and we’re not keen on it being our most prominent frontal feature.  We also don’t want to sit next to it on our patio out back, so we’ve shoved it 10m to 15m down the garden.  
 

We’re building an attached slightly oversized garage at the front of the house (to keep our campervan snug plus it looks ‘right’) which will be half the width of the plot and that’s where the MVHR is hopefully going - intake on one side exhaust on the other.  Ditto this sort of unit, if it ticks all the boxes.  Otherwise it’s a remote monoblock ASHP amongst the daffodils.  

Edited May 7 by G and J
clarity and typo removal

[joe90]

Understood.