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Heat Pumps - Yes/no Or Maybe...?


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#16 IronmanG

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Posted 28 October 2021 - 04:44 AM

I reckon the problem is they simply aren't a stand alone solution.

#17 sonscar

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Posted 28 October 2021 - 07:38 AM

Cynically I suspect it was computer modelled by the sellers of the kit.All the models giving the wrong answer were dismissed and then the successful concept sold in a"gentlemens club"to tame government advisors.If planned as  a QUALITY new build I have no doubt the concept may work but as a one size fits all solution it may be less than ideal.

I agree we need to do something but when internal air travel has just been made cheaper.antarctic cruises,container ships full of plastic tat etc etc,you get the idea.A radical solution would be stop making stuff(back to "gentlemans club" whispering),Steve..



#18 PoolGuy

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Posted 28 October 2021 - 09:09 AM

I won’t be taking things seriously until patio heaters are banned. We have an ‘eco shop’ in the High Street, they bang on about bringing your own containers for the products that they sell, one of the women who runs it turns up in a massive Volvo suv (she lives within walking distance) and switches on the patio heaters as she opens the shop, well I suppose if your prepared to pay a premium for mediocre coffee, you want to be warm while you drink it. 



#19 1984mini25

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Posted 28 October 2021 - 10:45 AM

Similar type place near me I largely ignore.

 

I’ve got several neighbours who think nothing of getting in the car to drive the 0.2 miles (according to goggle maps) to the local shop, sometimes more than once in the same day. All because the 0.2 miles is too far to walk (4 mins approx)

 

But then round hear every time the sun comes out/temp is above 20 degrees every other neighbour gets out the gas bbq (to the point all you can smell is gas/burning) or petrol lawn mower/strimmer.


Edited by 1984mini25, 28 October 2021 - 10:54 AM.


#20 Homersimpson

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Posted 28 October 2021 - 11:37 AM

I reckon the problem is they simply aren't a stand alone solution.

They are but like all things they need to be correctly designed by people who know what they are doing and sadly in many instances that isn't the case.



#21 Homersimpson

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Posted 28 October 2021 - 02:29 PM

I found this table on a manufacturers website which pefectly illustrates how the unit works at different external temperatures, flow temperature to radiators and how much power is required.

 

nvlOnu2.jpg

 

This is a 9kW single phase unit so suitable for a domestic house, at -7oC outside for a flow temperature of 50oC you get a heat output of 7.15kW and use 4.07 kw of power so the co efficent of performance (COP) is around 1.76:1, when its 7oC outside for the same flow temperature you get 8.1kW of heat and use 2.72kW of power which gives a COP of  2.98 which is much better.

 

The challenge is that you have to see how much power is uses over 12 months, in the winter on the coldest days it won't  be very efficent but as we don't get that many really cold days as a percentage of the year its how it performs overall thats important.

 

There are many issues but some of the bigger ones i've seen are:

 

  • Existing system isn't suitable for the heatpump (i.e. rads not increased in size as necessary or insulation improved).
  • Heat pump incorrectly sized due to wrong data on heat loss from property (designer guessing how much insulation is in place and getting it wrong).
  • Poor construction of the property, i.e. lots of air leaks increasing the heat loss above that designed.
  • Designers/installers providing the smallest unit they can which uses an electric immersion to top up heat for more of the year than it should do, there is some sense in doing this (as it reduces the cost of the unit) if the immersion is only for a few days of the year but if its on a lot then costs go up massivly as the COP on this is 1:1 (ignoring the minor electrical losses through cables etc).
  • Users not setting the unit controls correctly (although some of this is caused by a lack of understanding/explantation of the termonology involved and the responsibility for this rests with the installers).
  • People looking at the usage of the unit in more detail than they would for a gas boiler, a lot of people get this and because they have been told how efficent it is they monitor it more closely and are disappointed that it seems to use a lot of energy.  As many people pay their energy bills monthly and average it across the year, if you pay £100 per month for gas and electric 12 months of the year. and then the user monitors their new heatpump in january and its using £6 per day meaning the monthly cost will be nearer £180 they feel that the unit is inefficent, in reality its just does most of its work in the colder month and won't run much between april and september except for hotwater demand.

For them to become viable they need to be sold in much higher numbers so costs come down per unit and either the cost of electricity needs to reduce (or more likely as is happening now) the cost of gas will increase making them more attactive, especially as photovoltaic cells become more popular on houses.

 

The big elephant in the room that no one is considering is how the electricity network will cope with this, I went to a seminar for one of the electricity distribution network operators and their two hot topics they were working on were electric vehicle charging and heat pumps, cars are less of a problem as not everyone will put their car on charge at the same time and their studies showed that on average a person charged their vehicle once every three days. 

 

With heat pumps they were suggesting that users/installers needed to notify them before they were installed, I asked whether there is or was going to be any legislative requriement to do this and they said not at present.  When I asked them how they were going to enforce this there were blank looks allround and thats the issue, if everyone else on my estate has one I will want to put one in at some point but neither I or anyone else will want to pay the huge cost to reinforce the electricity network to do this.  At some point there will be a problem because when its cold its cold for everyone and we all want heat at the same time, there will be some diversity as not all units will be running at exactly the same time as they cycle on and off but the electrical load will still increase hugely.


Edited by Homersimpson, 28 October 2021 - 02:35 PM.


#22 sonscar

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Posted 28 October 2021 - 04:12 PM

Are these manufacturers figures achieved in the same way as car manufacturers work theirs out?Under laboratory conditions(real life figures may/will differ)User error?you mean you want to turn it up or down when you like?Open a door or window for ventilation?.
Were you mis sold a heat pump?lawyers will already being schooled.
As said above the electricity tap is barely keeping up with the use now.
Govt grant of 5K,quick, increase the price by 6k nicely done(you will be)
Only partly jesting,Steve..

#23 Homersimpson

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Posted 28 October 2021 - 05:21 PM

Are these manufacturers figures achieved in the same way as car manufacturers work theirs out?Under laboratory conditions(real life figures may/will differ)User error?you mean you want to turn it up or down when you like?Open a door or window for ventilation?.
Were you mis sold a heat pump?lawyers will already being schooled.
As said above the electricity tap is barely keeping up with the use now.
Govt grant of 5K,quick, increase the price by 6k nicely done(you will be)
Only partly jesting,Steve..

The figures will all be tested in a lab but unlike a car they are very specific tests so if a manufacturer says that their car does 60mpg on the motorway that means a specific test at specific speed done in a way that makes it most efficent with a driver who is driving it in a way to maximise the figures.  With a heat pump they simply turn it on in a chamber that is at whatever temperature they want to test at and measure the heat output energy and temperature and power input.

 

If it were a car it would be a test of MPG against power produced against speed at a given thottle input and then testing it at various points across the range.

 

In that way its more like testing a lamp (light bulb) how much light does it give out when its on and there isn't a lot they can do to fiddle the results, i'm sure there are some variables and they would make sure that the heat pumps they test are built to the best tollerances but generally they can't influence the figures that much unless they outright lie and thats going to get them found out fairly quickly when people are cold or energy bills are high.


Edited by Homersimpson, 28 October 2021 - 05:23 PM.


#24 PoolGuy

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Posted 28 October 2021 - 06:15 PM

 

The big elephant in the room that no one is considering is how the electricity network will cope with this,

Looking at that point from a slightly different angle, how will the average house supply cope? Most houses have a 100amp supply, your example heat pump draws 37amps (plus the immersion?), a modest induction hob draws 30amps, a single oven draws 20 amps, there's not much left over for the rest of the house, and that's without factoring in an electric car charger, or a swimming pool heater  :D



#25 Homersimpson

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Posted 28 October 2021 - 06:34 PM

 

 

The big elephant in the room that no one is considering is how the electricity network will cope with this,

Looking at that point from a slightly different angle, how will the average house supply cope? Most houses have a 100amp supply, your example heat pump draws 37amps (plus the immersion?), a modest induction hob draws 30amps, a single oven draws 20 amps, there's not much left over for the rest of the house, and that's without factoring in an electric car charger, or a swimming pool heater  :D

 

The heat pump above has a maximum input power of around 4kW for a 50oC flow temperature which is about 17.4A, an electric oven and hob have quite a large diversity and my electric double oven and induction hob as an example only need a 32A circuit breaker based on the diversites in the IET On-site guide.  The piece of cable from the street to the house will almost certainly be fine but where this meets the main in the road back to the substation thats where the problem starts, mains supplies to houses generally have one large main cable down the road and the houses tap off this (spread across the three phases).

 

If they have 60 houses each with a 100A supply (and bearing in mind its a three phase main so its 20 on each phase) the cable in the road wouldn't be rated at 2000A per phase.  When I used to do a bit of residential work for housing estates the local electricity board advised that they allowed 2.2kW (around 9.6A) per house for a typical house with non electric heating (oil, gas etc.).  The three phase main will probably be rated/fused at around 300A.

 

If they have bit of an overload for a short period (world cup half time with all the kettles being switched on for example) then they accept that the system is overloaded for a short period.

 

If you have a house with a swimming pool then you need a bigger supply but to be fair the few houses I worked on with pools had bigger supplies and the owners name was usually sheikh!



#26 sonscar

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Posted 28 October 2021 - 06:57 PM

Homersimpson,exactly what I said,,test in a lab is different to real life.have you been sold a diesel car?did you buy a Volkswagen?These were passes in the lab tests they were subjected to.Later someone did not like the test as it did not reflect real life so you need compensation.
I am very cynical because I have felt royally ripped off by anything that has been "sold" as the newest answer.Fortunately I am in my twilight years.Steve..

#27 Homersimpson

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Posted 28 October 2021 - 07:33 PM

Homersimpson,exactly what I said,,test in a lab is different to real life.have you been sold a diesel car?did you buy a Volkswagen?These were passes in the lab tests they were subjected to.Later someone did not like the test as it did not reflect real life so you need compensation.
I am very cynical because I have felt royally ripped off by anything that has been "sold" as the newest answer.Fortunately I am in my twilight years.Steve..

Well not quite, unlike a car MPG test where the manufacturer can choose a benefical test route, avoid traffic and use a driver with a light foot and have loads of goes to provide figures that don't represent real world conditions(especially if you live in a hilly area or get stuck in traffic) a heat pump manufacturer can't play with the variables to fudge the figures.

 

With a heat pump the input power is what it is, the outside temperature and water output temperature are whatever the test requires and the heat output is what it is.  If they test at -7oC outside temperature and want to achieve a flow temperature of 50oC then the input and output power/heat is what it is, there isn't anything they can do to improve things without lying.

 

I'm not saying fudging results doesn't happen and the VW emmissons scandall and the Grenfell Tower cladding fire test are examples of how this is done but in general a manufacturer would be mad to fudge a test for something thats easy to check and likely to be a problem, if the heat pumps don't do what they say when its -7oC outside or whatever then they will soon have a lot of complaints from people in the first 12 months while still in the warranty period.

 

Also if a manufacturer was claiming significantly better figures than competitors would soon be picked up on and checked, especially when the complaints started rolling in from customers.  Just look at the issues with the Nibe Fighter units and while it hasn't helped the people who ended up with the initally it has then helped other people to avoid the same problem.

 

I guess my point is don't dismiss the technology just because there are some issues with it and it operates different to what we are used to.  Gas boilers have their downsides as well, the main one of which is the high carbon emmissions and while there is still a high carbon content to electricity its reducing all the time, I checked the other day and 45% of electricity to my area was coming from renewable sources with 35% from carbon sources, 16% from nuclear and 4% listed as other.

 

Afterall what was wrong with points, condensor and a choke, nothing unless you wanted it to start first time in the dead of winter, there is always progress and a few false starts and the car industry has shown us that over many years but heat pumps are a proven technology that has been around for years but just not yet caught on in the domestic market in the way they perhaps should have because of the cost and the fact that gas has always been significantly cheaper than electricity.



#28 blacktulip

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Posted 30 October 2021 - 06:51 PM

Put on your woollies I say 😂

Edited by blacktulip, 31 October 2021 - 10:09 AM.


#29 mab01uk

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Posted 31 October 2021 - 10:45 AM

£70,000 in grants for a heat pump - but it still saved us NOTHING... and it's so chilly our daughter keeps her coat on indoors

The Roche family now question their decision to have the heating system installed in their detached four-bedroom home, situated in the village of North Luffenham in Rutland:-

https://www.thisismo...ed-NOTHING.html


Edited by mab01uk, 31 October 2021 - 10:45 AM.


#30 PoolGuy

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Posted 31 October 2021 - 11:16 AM

£70,000 in grants for a heat pump - but it still saved us NOTHING... and it's so chilly our daughter keeps her coat on indoors

The Roche family now question their decision to have the heating system installed in their detached four-bedroom home, situated in the village of North Luffenham in Rutland:-

https://www.thisismo...ed-NOTHING.html

They've obviously had the wrong system installed...






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