Air Source Heat Pump

[MrBadger]

I'd urge a bit of caution with regard to the Navitron forum. It's owned by a supplier of heat pumps and other renewable stuff for a start, so discussion is often limited by the moderation team if it starts to veer off into the merits of products that Navitron don't sell.

A bit of common sense maybe. Yes, it is a forum owned by a company, but it is independently moderated by users and the only significant criteria they have is no links to other suppliers for projects that they sell themselves (they are not installers so installation advice is totally independent, but do have an installer list so prefer people to use them but its a polite preference not a rule and total independents are equally welcomed to be mentioned - its how I got my PV installer, nothing to do with Navitron or their products), which considering they foot the bill for the resource, is, imho, fair enough - a little like here and not linking to sites that are 'competitors' to TMC. I totally disagree about discussion being moderated for non Navitron products - absolutely not the case. In fact, products recommendations are very rarely mentioned and even they are, references to products not sold by Navitron are often talked about, just not links.

Like most forums, there are a couple of easy to spot things to tip toe around - I suspect the moderator that Jeremey was referring to is long gone and no longer concerned with the wellbeing of this planet, RIP. I was a regular for years, and imho, an excellent resource, I would not have recommended it otherwise. But there are others resources available to add to the knowledge base.

 

[Glan gluaisne]

I swapped from electric storage heaters to ASHP/radiators in a 2 bed bungalow, and achieved a COP of about 2. The biggest problem was that the heat pump was slightly oversized for the load (from radiators and DHW tank), and the control electronics wanted to ramp up the output to full power faster than heat would flow round the house - meaning it went off,ramp,full-power,over-temp in a continuous 20 min cycle (and couldn't heat the hot water in the summer without tripping the over-temp failsafe).

Still an improvement on the old system, but emphasises the risk of getting a badly specified install. Hopefully standard practice has moved on in the past 8 years too.

This sounds familiar. When I fitted our heat pump I found that the default settings were just crazy. The heat pump wanted to deliver a flow temperature that was proportional to outside air temperature, and was set to a flow temperature curve that meant it spent around 10 to 15 minutes per hour de-icing. Every time it de-iced it ran in reverse, pumping heat out of the house to melt the ice on the external heat exchanger fins.

I spent ages playing around with the settings, before finding a setting that significantly improved the efficiency. I also believe that it's essential to install a low loss header on the heat pump flow and return, in order to reduce the probability of the heat pump shutting down through low flow or over temperature.

I've now got our unit running at around a COP of 3.6 on average, after a lot of playing around. It is massively oversized (because it was available as surplus stock at a very good price!), as our worst case heating requirement is only about 1.6 kW, and that's when it's -10°C outside and 21°C inside. The heat pump is rated at 7 kW output, so never gets to run at anything close to its full output. Luckily, being inverter controlled, it can happily modulate down to an output of around 1 kW, which means it stays on for a long time, heating up our slab. It also means it doesn't ice up, as the evaporator is capable of dealing with a 7 kW output, so is never working hard when the thing is delivering around 1 kW.

Looked into this myself recently as I have an old, inefficient oil boiler. The running costs of an ASHP don't stack up, especially in winter when its actually cold outside when even my existing boiler beats it for price/kwh heat produced - a modern oil boiler would easily seem to beat an ASHP. One idea I do quite like though is a 'hybrid' system, e.g. something like this;

Grant VortexAir Range | Grant UK

This uses a combination of AHSP, modern oil boiler and immersion heater to make best use of heat sources depending on inside/outside temperatures, and will work with existing radiators - heat pump can bring the system up to its max temperatures, then the boiler can take over to top it up. Running costs should thus be lower than either a boiler or an AHSP running on their own.

Expect it'll be expensive, but has the option that you can just put a new boiler in now and then bolt on the heat pump later on.

In the short term I recon I can do better by keeping my existing boiler and getting some solar/powerwall and just using my existing immersion heater to heat water during the summer months, meaning I don't have to burn oil at all unless I need heating, but YMMV.

Hybrids are a really good idea for older houses, especially those with a high hot water requirement. A friend has been running a Daikin Altherma hybrid, which is essentially an ASHP with an LPG combi boiler boost heater, and reckons it's performance is excellent. Last time I spoke with him he'd not filled his LPG tank up for three years.

The only snag with hybrids is that I'm not sure where or not they are eligible for the RHI.

 

[Glan gluaisne]

A bit of common sense maybe. Yes, it is a forum owned by a company, but it is independently moderated by users and the only significant criteria they have is no links to other suppliers for projects that they sell themselves (they are not installers so installation advice is totally independent, but do have an installer list so prefer people to use them but its a polite preference not a rule and total independents are equally welcomed to be mentioned - its how I got my PV installer, nothing to do with Navitron or their products), which considering they foot the bill for the resource, is, imho, fair enough - a little like here and not linking to sites that are 'competitors' to TMC. I totally disagree about discussion being moderated for non Navitron products - absolutely not the case. In fact, products recommendations are very rarely mentioned and even they are, references to products not sold by Navitron are often talked about, just not links.

Like most forums, there are a couple of easy to spot things to tip toe around - I suspect the moderator that Jeremey was referring to is long gone and no longer concerned with the wellbeing of this planet, RIP. I was a regular for years, and imho, an excellent resource, I would not have recommended it otherwise. But there are others resources available to add to the knowledge base.

Just had a look there. It seems that it's a great deal quieter there than I remember from a few years ago, when I was booted off for being factual, when the last thing they seemed to want was to let facts get in the way of their good old rant. It does look as if the membership that remains there are mainly members that have been there for years, pretty much all I've just seen are names I remember from around 5 years or so ago, though, with not a lot of new members (at least from what I could see from a quick scan around).

It also still seems to have the same warning at the top of the page that anyone trying to join using something like a gmail, yahoo or similar, "disposable" email address won't get in. This may have been a sensible idea 5 or 10 years ago, but we now live in a world where it seems that the vast majority of people use an email address from these sorts of providers. I deal with around 10 to 20 new member requests a day on another forum, and at least 90% of them will be from providers like gmail, hotmail, yahoo etc. Could be why the Navitron forum doesn't seem to be seeing many new members, together with those, like me, that remember how appallingly the moderation people there behaved.

As a word of caution I'd have to add that Navitron don't seem to have applied any security updates to their forum software for a long time (years, from a brief look around), so the chances are that any personal details they store may well not be very secure. That's far from unusual, though, there are loads of internet forums around running on really old forum software, that's not been patched, as it takes a fair bit of effort to keep stuff like this up to date. I only became aware of the significance of this since seeing how often Invision (the provider of the software another forum uses) issue security patches and updates. On average it's around once a month or so, as potential vulnerabilities are found and patched.

 

[MrBadger]

Coming across as someone with a bit of a vendetta against them. I would have thought better of you.

 

[p_iv]

The only snag with hybrids is that I'm not sure where or not they are eligible for the RHI.

They are (or at least some are) but needs metering on energy actually used - https://www.ofgem.gov.uk/ofgem-publications/121703, page 2

 

[Glan gluaisne]

Coming across as someone with a bit of a vendetta against them. I would have thought better of you.

If you had been on the receiving end of the offensive messages I received from them at the time, then I suspect you might feel the same way. At the time I had received quotes from them for around £12k worth of stuff and I was trying to pin down an installation date from one of their installers.

When I forwarded on the pretty damned offensive message I'd had, the initial response from the company was that their forum was nothing to do with them (although they host it and pay for it and had sent me the link to it in the first place). Choosing not to deal with them because of this was a PITA for us, as it meant having to find two other suppliers at short notice, but given what had happened I wasn't going to go through with the purchase from them.

To be absolutely fair, someone from the company did get in touch with me a couple of months later to apologise, and explain that they were aware of their forum not being as good a showcase for their company as it might have been and that they were taking action to ensure that other customers didn't have a similar experience to us. This was too late for us, though, as I'd already switched suppliers. I got the feeling from chatting to the chap on the 'phone that selling direct to the public, via their installers, was not really their main interest, they seemed more focussed on selling directly to installation companies. I also got the feeling that he (perhaps as an individual, rather than as a representative of the company) felt that their forum was sometimes more trouble that it was worth.

 

[MrBadger]

I suspect the volunteer moderator in question had other things on his mind. He was terminally ill and died probably not long after.

Death of forum moderator Martin

People passionate about their cause, as Martin was, often come across as a bit disagreeable, as the above link affectionately shows...

 

[Glan gluaisne]

I'll respond by PM, as this is getting a bit off-topic

 

[Avendit]

Some good advice (on the first page at least ), just wanted to back up with our calculations.

1960's built chalet style house with 3 bedrooms in a very tall roof space. We had some extension work coming up anyway, an intention to get a tesla and a need to replace our (old, single pipe) heating system anyway. A friendly and in depth chat with the energy saving trust (scotland) including a long an informative visit from an adviser helped us realise this, see some predictions on costs and savings and model a few options. Doing some insulation upgrades and a new gas boiler would have saved us more £££, but an ASHP should still save us a chunk, and saved many more CO2's. So we decided to skip a generation and go Heatpump.

To back the heatpump up and give it a chance we are getting a new heating system - rads will actually stay the same sort of size we are used to, but are much bigger than a boiler install would have. We will get underfloor in the new area, which will also be build to code (didn't have time to go passivhause), but I'll be keeping an eye and the contractors know that quality of installs are key, and I'm going to adjust a few details around windows to help stop cold spots.

We are also getting the old bit of the house drastically improved by using some spray foam insulation. With the complex room-in-roof and dormers we have, no traditional companies would touch it and this should address insulation and air tightness in one fell swoop.

We should be able to get interest free loans for most of this.

The ASHP we are going for is a 12KW panasonic one. Our calculated heatloss by both the heating company and the EST people was about 10KW, plust hot water. If, closer to the time we have the spare cash we will upgrade that to one of their T-CAP units which has consistent output down to ~-15degC, just for reassurance more than anything. The unit we have selected runs at ~12 Amps only.

Luckily everything else on our street side and our meter was 100 Amp capable, so when we did a load check with the Heatpump, a charger allowance and induction cooking, the guy that came to assess could just whack in a 100amp fuse for free. Might be worth checking why you are limited to 80amp - is it just your meter, or is there something bigger?

Especially in an old building, key will be adding insulation so you don't need such a big pump too. The same as the Tesla is a balance of increasing battery capacity and increasing efficiency of all parts of the system, so must a heatpump be, or disappointment will ensue. And get a second quote - looks like someone is screwing up some numbers. I'd happily put you in touch with our guys, but they are Scottish central belt focused so probably not much use.

 

[Christiez]

Just reviving an old thread now I have an update.

Managed to get a few quotes and the below worked out to be the most competitive;

Building Requirements
- Total Floor Area (m2) 137
- Heat loss W/m2 - 68
- Space Heating Load (kW) 9.7
- Space Heating (kWh/yr) 20358
- Hot Water Heating (kWh/yr) 3021

System Breakdown
- 12kW NIBE F2040 ASHP
- 250ltr Joule ‘High Gain’ Hot Water Cylinder
- 40l NIBE UKV buffer tank
- Circulation pump
- Installation components
- Electrical components
- Pipework from heat pump to cylinder
- Delivery

Total Price: £10,990.33
Estimated Annual RHI Payments: £1,556

Before I progressed this further, I wanted to ensure that I wouldn't have any issues with the 80A fuse so contacted Western Power. I got the following response;

On the application I received the installer has stated the maximum demand required at your property is 100A. unfortunately with you having a EV charge point and also looking at the possibility of a heat pump, a single phase 100A supply could not be offered. The reason being is WPD cannot guarantee that the temperature at the fused cut-out can be kept below 20 degrees during the period of the maximum demand. This is down to the thermal rating of the fused cut-out.

The options available

- Install a load limiting device to ensure the overall demand is maintained to a safe level e.g. <80A or install a load limiting device to ensure that an EV charger is not used during the existing high demand period. Many EV installers offer this functionality. The device must be fail safe, hard wired and operate within 5 seconds.
Or
- Undertake a full load study at the property
Or
- Upgrade the existing single phase connection to three phase 80A per phase (Looks like this starts from £1,500)

The company I have been liaising with regarding the ashp installation put me in touch with another company who specialise in EV charging. They have suggested I replace my Rolec as it doesn't support load balancing and replace with a Zappi at a cost of £850 + VAT...

So I'm a little confused on the best way forward here, I feel like there must be a better/cheaper solution than replacing the chargepoint or upgrading to a three phase supply - or are these the only options?

Thanks in advance for any advice.

 

[Avendit]

Progress at least!

I think I did a full load study - turned out to be a simple 2 page word doc. And after that they were happy to give me 100a for a full electric house, although we run showers from the tank, not electric heater. Would be worth asking what this may entail?

 

[Christiez]

Progress at least!

I think I did a full load study - turned out to be a simple 2 page word doc. And after that they were happy to give me 100a for a full electric house, although we run showers from the tank, not electric heater. Would be worth asking what this may entail?

True, progress can only be a good thing!

That's interesting about the full load study - think it's definitely worth me exploring further.

 

[MrBadger]

Is there much scope for more insulation / air tightness to get your space heating requirements down and maybe give the option for a lesser load?

 

[vitesse]

Frustratingly I already had to fork out £500 for the last upgrade so hope they take pity on me!

That's crazy unless they had to upgrade the cabling or something to your house as when I had my charge point fitted and switched to energy suppliers the smart meter fitter upgraded the fuse from 60A to 100A free of charge.

EDIT I'm guessing it IS much more than just a fuse upgrade!

 

[Christiez]

Is there much scope for more insulation / air tightness to get your space heating requirements down and maybe give the option for a lesser load?

This is certainly something I'm looking into and recently been up in the loft to put down more insulation (300mm now). I've also had a new EPC done so I can then focus on other areas but with it being a 1900s build I think it's going to be something that is tackled over time.

 

[Christiez]

That's crazy unless they had to upgrade the cabling or something to your house as when I had my charge point fitted and switched to energy suppliers the smart meter fitter upgraded the fuse from 60A to 100A free of charge.

EDIT I'm guessing it IS much more than just a fuse upgrade!

You're right, that is crazy! When I initially spoke to the guys fitting the charger they said themselves that more often than not it's done foc but I wasn't so lucky.

 

[vitesse]

Before going for a heat pump, you need a detailed energy survey for the property. Heat pumps in houses not designed or upgraded to use one is a recipe for disappointment. Heat pumps work in a completely different way to a normal boiler heating (fundamentally low heat output for long periods of time vs high output for short periods) wise and that does not work well in spaces that cannot cope with that, ie the majority of UK homes. I worked with someone who did exactly what you are proposing, they were never happy even after several attempts to fix. I looked into this too and still running on gas even though I have done a reasonable amount to our house to make it thermally more efficient and still more to do but there is only so much you can do to regular UK housing stock - enough though to run MVHR well which needs good air control. Jeremys heat uses are not typical because his house was designed specifically for low energy use, so his numbers will not be typical. A heat pump is not a silver bullet although some installers may try and paint that picture.

You put your head down the heat pump rabbit hole, you may never return. Ask the same question on Navitron Renewable Energy and Sustainability Forum - Index - they know about EV's, electrical, insulation, batteries etc etc and quite a few are off grid. That is full of helpful people who have tons of experience doing this on regular UK building stock and what works, what doesn't and what installers do get wrong. And remember, insulate, insulate, insulate, thats the best saving you can make.

I remember a consumer rights/watchdog time programme highlighting problems with a new-fangled heating system installed in a new estate a few years back. Does that ring a bell - I suspect that was an air source heat pump system which wasn't properly specced and/or installed.

 

[Maz0]

I live in a 1880 3 bedroom cottage, stone walls meter thick. I researched the ASHP route and found most people I spoke to had more complaints than compliments. In fact in many cases people were paying high electricity costs just to operate a pump that wasn't even doing anything. The costs to install in the 10-20k range could buy my oil for the next 20 years at the current prices. In the end it was much better to fix the heating system we had with better radiators, insulation where possible to limit heat loss etc.

Watch some youtube videos on them, there are some real horror stories of folk with 15k of equipment in "plant rooms" like sheds and when things break its another grand here or there. If that happened you would wish you were just spending that money on good old reliable oil.

It's a bit like that other thread on the Powerwall, sometimes it just doesn't make financial sense and it didn't in our case, even without calculating for breakages.

 

[Avendit]

You have to watch tho, as you will find many of the horror stories are pretty old now. Even in the last 2 years heatpump design and ease of installation and suitability have really improved.

Equally, I'm hoping for price equivalence with our boiler, not to save much. That's after a £12k install, new radiators (needed anyway) and probably £5k of insulation work (getting spray foam insulation to insulate and seal in one fell swoop).

Our house is a toughy tho. Not old enough to have style, not new enough to be built to any kind of standard. But as we were modding it any way, and boiler and rads were up for a renew anyway, and insulation is always good to have more, this all makes sense.