Vastly lower real world energy requirements than the Heat Pump tool kit spreadsheet suggest. Should i trust the sheet?

[Bashers]

I've been looking at a heat pump and sizing it based on the actual gas used to heat my house.

Am i being stupid and this is real world data irrelevant as suggested by the heat loss calculator floating around?

 

I've filled out as best i can, and over estimated the dreaded over-garage ensuite thats built to air change standards from the mid 16th century, not sure why they bothered with the window, but i digress. 

 

Its suggesting i need 5.3Kw per hour every hour during the coldest times.

My actual usage during the coldest days of 2022 were 83Kw/day, or 3.45Kw/h

 

If most installers are using the vastly rounding up figures before adding to the sheet, then overestimated figures on these sheets, then adding a pinch of salt and upgrading to the next bigger ASHP, i'd be on a totally unneccessary 12kw heat pump, whereas the 5kw unit, "flat out" would just about cut it.

 

 

[JohnMo]

Your not comparing apples with apples. 

 

Your daily usage is measured in kWh and is affected by the outside temperature, if it is warmer than -2.5 outside your heat losses will be lower - so less gas used.  Your gas consumption also incudes DHW. 

 

The spreadsheet is calculating the heat power required on the coldest day -2.5, expressed in kW. 

 

So if the outside temp was at -2.5 for 24 hrs, you would require a heat input power of 5kW to keep a stable temp inside, so you would use 120kWh of energy that day

[Bashers]

(theres no hot water in the calculation or the gas usage as thats on a seperate standalone water heat pump.)

i believe am comparing correctly. the google sheet shows me what the house (possibly) loses in one hour, 5kw, on the coldest day 

the gas usage is what is used to correct that heat loss in 24 hours, 83kw, including inefficiences, on the coldest day when we had -10°

so 83 kw divided by 24 gives me 3.45kw per hour does it not.

[SteamyTea]

W is power, a joule per second.  The joule is the SI unit of energy and can be converted to Wh by multiplying by 0.0002777778

A kWh is 1000 [the k] multiplied by W [watt] multiplied by time in hours [h].

 

I think you are getting confused with kW and kWh.

There is no kW/h, or kW per hour.

 

5 minutes ago, Bashers said:

83 kw divided by 24 gives me 3.45kw per hour does it not.

No

it gives a power of:

 

83 [kWh] / 24 [h] = 3.5 kW (to 1 decimal place)

That is the power that the heater is giving out, on average, for 24 hours.

 

kWh / h  the h [hours] cancel out to leave the kW, the power.

 

Edited February 16, 2023 by SteamyTea

[JohnMo]

Leaving aside the units being all messed up - if you need a 3kW or 6 kW ASHP at -2.5 you most likely end up with the same unit, once you start looking the actual performance at low temps, as not all manufactures rate their units the same, some will say the unit is 6kW, but at -7 only produces 3kW other will say 6kW but produce 6kW at -7.

 

 

[Gareth J]

Another thing to consider; you will potentially use a heat pump differently to the gas boiler. Maybe not, but it could make a difference.

 

If you currently run the heating a few times a day (say, first thing in morning, home from work and just before bed) to get the air in the house up to some acceptable temperature, switching to a lower power, but more constantly run setup, could use more energy overall. Or result in the house not getting to the temperatures you'd like at the times you'd like. Or both.

 

Unless your coldest day gas usage was based on running the heating system 24/7. And, ideally, for the best comparison, at the same flow temperature as the heat pump will run at (unless planning to change emitters at the same time)

[JamesPa]

For what its worth my personal experience is this:

 

• MCS survey/heat loss calculation based on 'assumed' levels of insulation and costing me £350: 14kW at -2
• My heat loss calculation based on the above, but putting in more realistic estimates for the insulation: 11kW at -2
• Actual measured gas consumption (I still have gas heating - working on the conversion) when it was -2 outside for 5 days in a row: 7.5kW

 

The last figure was based on leaving the heating on 24x7 which is what would most likely happen with an ASHP.  If I turn it off overnight then it shoots up  temporarily to about 9-13kW for a couple of hours in the morning (depending on outside temp).

 

My speculation on the differences between my estimates and the actual measured is

 

• some of my windows may be better than I assumed (incidentally, swapping out the glazing units in 30 yr old double glazing seems to make a material difference)
• my ventilation loss may be less than the assumed value 

 

But I can't prove either

 

Hope that helps calibrate expectations on the precision of the calculations.  I think there are, unfortunately, quite a few unknowns.

Edited February 16, 2023 by JamesPa

[Bashers]

I've test been running with a flow temperature between 45 and 50 degrees for a few months now, so i expect not to have to change any emitters, and we run the heating 18 hours a day modulated by the tado thermostats in a fairly decently insulated home.

Before anyone jumps in re the hot water, thats handled by the water heater seperately

So yes we get a burst at 4 or 5am when it starts up, but that accounts for the 6 hours its been off.

We're not the type to turn it on when cold and off when hot. Its left active spring to autumn and will silently keep temperature to within 0.2 degrees of where we want it

By all accounts were doing well with it, apart from that ensuite above the garage

 

So my assumption is that if we use 84 "units of heat" per day when on gas heating and its -10 outside, we'll require 84 "units of heat" from the ashp unit. so divide that by 24 and we arrive at 3.5 required every hour

So, if the maths reckons 5.3kw then theres a definite inflation going on.

However, i dont think i'm going to chance it with a 5kw unit, 8kw seems more prudent

[JamesPa]

I'm taking much the same approach as @Bashers.  Measuring a real world consumption of 7.5kW gives me the confidence to go with an 11.2kW unit to match my calculations, rather than a 14kW unit that the MCS bods want to sell me.

 

My only remaining problem is that I need it 'installed to MCS standards' to pass permitted development.  So far I haven't found an MCS registered installer who interprets 'installed' as anything other than 'surveyed (chargeable), designed and over-specified (chargeable), installed (chargeable), all existing perfectly good sundry components thrown away and replaced with new, quite possibly not so good, components (chargeable and environmental vandalism), configured (possibly badly but still chargeable), MCS 'consultancy' (chargeable).  Hopefully I eventually will!

[dpmiller]

34 minutes ago, JamesPa said:

So far I haven't found an MCS registered installer who interprets 'installed' as anything other than 'surveyed (chargeable), designed and over-specified (chargeable), installed (chargeable), all existing perfectly good sundry components thrown away and replaced with new, quite possibly not so good, components (chargeable and environmental vandalism), configured (possibly badly but still chargeable), MCS 'consultancy' (chargeable).  Hopefully I eventually will

 

give the guys at Cool Energy a shout and see if any of their installers can assist.

[JohnMo]

1 hour ago, JamesPa said:

installed to MCS standards'

So the question is do you have to be a certified installer to install to MCS standards?

 

Or can anyone follow the guidelines and complete a MCS standards install?

 

You can install solar PV to the prescribed standard without being certified, so what's the difference?

[Radian]

1 hour ago, Bashers said:

I've test been running with a flow temperature between 45 and 50 degrees for a few months now, so i expect not to have to change any emitters, and we run the heating 18 hours a day modulated by the tado thermostats in a fairly decently insulated home.

 

Can you 'range rate' your gas boiler? Most seem to have this facility somewhere in the installer menu - even my 15 year old Glowworm has it. How low you can go depends on the modulation ratio for your model. Mine is a 30kW boiler and only has a 3:1 modulation ratio but it still lets me 'try out' a 10kW heat source (minus a bit for calorific conversion). I've dropped my flow to 50^oC and am slowly lowering the range rating. Currently at 15kW. You'll understand why I'm going cautiously if you compare my Bright data with yours 😆

 

[JohnMo]

2 hours ago, Bashers said:

flow temperature between 45 and 50 degrees

You really need to be dropping that another 10 degrees or more to get a good CoP. A 2 degree day and 50 flow temp is good for a CoP no better than 2.8.  A flow temp of 35 deg on the same day is 3.8 CoP.

[joth]

1 hour ago, JohnMo said:

So the question is do you have to be a certified installer to install to MCS standards?

 

Or can anyone follow the guidelines and complete a MCS standards install?

 

You can install solar PV to the prescribed standard without being certified, so what's the difference?

I think the key thing required for PD is it's installed to MCS noise limit standards. (Which is a system design as much as install task but whatever)

 

The real problem is if you find someone to do just this bit, getting the to document it, and persuading the solicitor of whoever eventually buys said house to accept said documentation.

If you don't intend to sell, then unless you have particularly pernicious neighbours or it's highly visible location, you'll probably be fine to install it regardless and no one would be the wiser about this requirement.

 

[JamesPa]

2 hours ago, JohnMo said:

So the question is do you have to be a certified installer to install to MCS standards?

 

Or can anyone follow the guidelines and complete a MCS standards install?

 

You can install solar PV to the prescribed standard without being certified, so what's the difference?

The MCS planning standards, which must be met for PD, expressly say that the installation must be carried out by an MCS registered installer.  Clever eh?

[JamesPa]

3 hours ago, dpmiller said:

give the guys at Cool Energy a shout and see if any of their installers can assist.

Will they install HP other than those made by Cool Energy (to which I have no particular objection, just that Id pretty much settled on the Mitsubishi and I cant quite get a CE one to tick as many of the boxes in my awkward retrofit)

 

1 hour ago, joth said:

I think the key thing required for PD is it's installed to MCS noise limit standards. (Which is a system design as much as install task but whatever)

 

The real problem is if you find someone to do just this bit, getting the to document it, and persuading the solicitor of whoever eventually buys said house to accept said documentation.

If you don't intend to sell, then unless you have particularly pernicious neighbours or it's highly visible location, you'll probably be fine to install it regardless and no one would be the wiser about this requirement.

 

 

Of course you are absolutely right, but MCS very cleverly wrote the 'MCS planning standards' to specify that the installation must be carried out by an MCS registered installer (as well as meeting the noise spec)

 

One MCS installer quoted me for a system which doesn't meet the noise spec (I told him all the key dimensions when he came round to visit).  When I challenged him on this point his response was 'well we will sort that out somehow, would you like me to book you in for the heat loss survey (£350)?'.  I think everyone here can guess what my answer was!

 

As it happens I doubt my neighbour will complain.  My worry is that I applied for planning consent (hoping to avoid MCS), was granted it, but with an unachievable noise spec (10dB below background, background is ~38dBA).  Its nuts of course, even background isn't audible indoors, much less 10dB below, and when the HP is making at its loudest everyone will be indoors.  But it puts me on a sticky wicket if there is a complaint and I cannot show that I have conformed to the PD requirements.

Edited February 16, 2023 by JamesPa

[Bashers]

So, within permitted development, I can install as many noisy non inverter air con units on my outside wall for the luxury of a cool room.

But if I want to install a single heat pump to reduce bills and do some good, I need super quiet unit installed with a hefty MCS markup?

 

 

[JamesPa]

9 hours ago, Bashers said:

So, within permitted development, I can install as many noisy non inverter air con units on my outside wall for the luxury of a cool room.

But if I want to install a single heat pump to reduce bills and do some good, I need super quiet unit installed with a hefty MCS markup?

 

 

Cynical though I am I don't think Aircon is permitted development.  Why do you think it is?

[JohnMo]

3 hours ago, JamesPa said:

Aircon

Air 2 water or air 2 air, they are both heat pumps. So no difference with respect planning rules.

[JamesPa]

 

13 minutes ago, JohnMo said:

Air 2 water or air 2 air, they are both heat pumps. So no difference with respect planning rules.

Exactly (so far as I am aware), which is why I asked @Basherswhy he thinks aircon is PD.

[JamesPa]

On 16/02/2023 at 09:39, Bashers said:

I've been looking at a heat pump and sizing it based on the actual gas used to heat my house.

Am i being stupid and this is real world data irrelevant as suggested by the heat loss calculator floating around?

I'm not sure anyone has yet answered directly the question you asked.  So far as I can see, if you need an MCS certificate, the answer is yes, real world data is irrelevant. 

 

The new standards MIS3005-d (design) and MIS3005-i (installation) appear to require a theoretical design according to a specified methodology, require that an installer issuing an MCS certificate has subcontracted design to or has designed according to MIS3005-d (or vice versa), forbid the customer from separately contracting design and installation, and nowhere mention real world measurements.  Oh and just for good measure if manufacturer instructions depart from the standard then the latter is to be applied.  Incidentally if you were thinking of reusing a hot water cylinder and the insulation of cylinder and pipes aren't up to latest standards, forget that also.

 

So sorry, if you want an MCS certificate (at least according to my reading of the standards) and wish to take into account real world data or how you use your house, forget it.  Resistance is useless!

 

I'm hoping someone on this forum is MCS qualified and tell me I'm wrong.

[sharpener]

It's a classic instance of a cartel. If OFGEM were not so useless they would do something about it in the interests of competition.

 

So I am not expecting to find anyone willing to add an ASHP to my present setup, because of the solid walls and my wish to include in the calcs the AGA, the woodburner and the MVHR, and not to rip out much of my existing kit including internet-based controls and a Honeywell Evohome zoning system (no don't start on about zoning, I have my reasons). Howewever even a modest CoP will beat my 28 y/o oil boiler on cost even before factoring in any free PV.

 

Similarly I had great difficulty finding a contractor to install 8 PV panels to wire up to the MPPT on my battery setup because it was not a standard MCS-type installation. Ironically I got an MCS certificate in the end including the notional supply of a meter which never left their stores, because the people I eventually found said they could not issue the certificate without a serial number. No metering required or indeed practiable at 48V DC.

Edited March 8, 2023 by sharpener

[JamesPa]

 

58 minutes ago, sharpener said:

It's a classic instance of a cartel. If OFGEM were not so useless they would do something about it in the interests of competition.

 

So I am not expecting to find anyone willing to add an ASHP to my present setup, because of the solid walls and my wish to include in the calcs the AGA, the woodburner and the MVHR, and not to rip out much of my existing kit including internet-based controls and a Honeywell Evohome zoning system (no don't start on about zoning, I have my reasons). Howewever even a modest CoP will beat my 28 y/o oil boiler on cost even before factoring in any free PV.

 

Similarly I had great difficulty finding a contractor to install 8 PV panels to wire up to the MPPT on my battery setup because it was not a standard MCS-type installation. Ironically I got an MCS certificate in the end including the notional supply of a meter which never left their stores, because the people I eventually found said they could not issue the certificate without a serial number. No metering required or indeed practiable at 48V DC.

I wouldn't give up quite yet.  Its not obligatory to have MCS to install a heat pump.  Its only obligatory if you want to install under permitted development (PD) or a government grant.  So one possible route, the route I am attempting to follow, is to seek express planning consent for the installation even though it could be done under PD, and then just self install or get a non-mcs plumber to install (assuming you can find one).

 

The problem I have encountered with this route, is that my LPA has imposed unachievable (and wholly unnecessary) noise constraints (10dB below background, in an area where background is totally inaudible indoors).  These go well beyond those which would be required under PD.  I have been fighting with them for the past 3 months, and they have finally conceded that they could relax the constraint, but only if I submit another planning application (£204), an application for the variation of a condition (£234), or appeal the decision (£0, but it takes 30+ weeks).  They have even gone so far as to suggest that I could install without permission and the probability of enforcement action is very low, albeit that they (obviously) could not recommend this. 

 

I don't blame the individual planning officers or the LPA for this obvious nonsense, successive government-imposed cuts to local councils means that the LPA has, for many years, been unable to recruit adequate staff numbers, unable to train the staff adequately, and unable to pay the salary necessary to attract away from developers any but those willing to make significant sacrifices in their own personal wealth in order to benefit the cause of public service.  Unfortunately that's the absolutely inevitable consequence of a government which prioritizes tax cuts over effective public service.  

 

The relationship between MCS and permitted development in relation to heat pumps is, in my view, a disgrace.  Because of the way MCS (a non-governmental body) have written MCS-020, they have imported into planning legislation matters which belong only in building regulations or consumer protection, and in doing so created a near-monopoly.  I can tolerate such things when government grants are involved, but not when they affect planning legislation which relates (or should relate) to the effect on others only or on very strategic matters. 

 

For my ASHP installation I am probably going to submit another planning application, although I resent the cost.  My fear is that either the planning officer or the environmental health officer will change during the interim, and I will be back to the start.

 

Incidentally I am having similar problem to that you quote with my plan to extend my solar panel installation.  Solar is currently a boom industry again, and so lots of companies have sprung up offering 'ready made solutions'.  That's fine, unless your needs don't fit their 'quick fix, quick buck' model.  I am still hoping to find a niche player who isn't in this 'sell your solution and make a quick buck come what may' business.  If not the remaining possibility is that the market will eventually cool again, and then only those who can be responsive to actual customer needs will survive.

 

 

 

 

[sharpener]

Having a disfunctional LPA myself you have my sympathy and thanks for drawing this to my attention. The Planning Portal says <Development is permitted only if the air source heat pump installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020) or equivalent standards.>

 

So who decides what are "equivalent standards"? If I produce an elaborate spreadsheet and tell them that in my professional judgement as a Chartered Engineer the MCS standard is not adequate to cover the additional heat sources in my scenario so I have used an appropriate design methodology what will they do? The site adjoins an 'A' road, apart from noise level what possible public harm can there be, the visual intrusion aspect is covered elsewhere anyway.

[JamesPa]

9 hours ago, sharpener said:

The Planning Portal says <Development is permitted only if the air source heat pump installation complies with the Microgeneration Certification Scheme Planning Standards (MCS 020) or equivalent standards.>

 

So who decides what are "equivalent standards"? If I produce an elaborate spreadsheet and tell them that in my professional judgement as a Chartered Engineer the MCS standard is not adequate to cover the additional heat sources in my scenario so I have used an appropriate design methodology what will they do? The site adjoins an 'A' road, apart from noise level what possible public harm can there be, the visual intrusion aspect is covered elsewhere anyway.

 

I don't know who decides what are equivalent standards, but I did ask Flexi-Orb, who are creating/have created alternative standards (to MCS) for solar panels, whether they also had ones for ASHP and their answer was that they intended to work on them but the accreditation process was many months long so it would be some time before these were in place.  So I presume that standards are accredited by some accreditation body like BSI.

 

The risk in just proceeding anyway with a development that complies with the PD requirements, other than that it is not installed to MCS standards by an MCS installer, is small.  In practice the LPA will only take action if there is a complaint.  Most likely, if there is a complaint, the environmental health officer (EHO) would investigate whether planning consent had been given, find that it had not, then could possibly, following further investigation and if there were sufficient evidence, issue a noise abatement notice.  Noise abatement notices generally require a log of repeated occasions, and given that long cold spells (triggering the ashp to run at max) occur relatively rarely, it might be difficult to obtain a log.  However if they did have sufficient evidence to issue a notice, it would be difficult to avoid complying and a valid notice would, I suspect, trump planning law. 

 

Alternatively Planning, having been alerted by the EHO, could issue a planning enforcement notice.  You could of course then apply for (retrospective) express permission, which might attract an unworkable noise condition, and you could appeal a noise condition more severe than the PD condition.  This would take many months during which Planning would be unlikely to enforce.  All of that gives you some time to install some noise mitigation measures, if the site allows it.

 

You could also try to argue that the PD rules are clearly intended to call up the noise related aspects of MCS020 not the other requirements therein i.e. to install to MCS standards and use an MCS installer.  However I fear that this argument would not hold up with officialdom, and possibly not even in the courts, unless there is strong evidence in Hansard or other official records to support the argument.

 

All of the above is pretty unlikely to arise if, in fact, there is no noise or minimal nuisance caused.

 

The other risk of course comes when you sell the house.  If the conveyancer is on the ball and checks for planning consents, they will find there is none and no amount of spreadsheets that they don't understand is likely to convince them.  This could conceivably cause a hiccup or, if the buyer were particularly risk averse, a withdrawal (although the buyer could probably insure against the risk and ask you to pay the premium).

 

if you were installing a gas boiler with noisy flue adjacent to your neighbours window, or a noisy oil boiler ditto, you could just go ahead without all of this discussion and speculation.