UKPN vs ASHP!

[Tony K]

Happy New Year all.

 

I planned to heat my new bungalow (100m2, flat roof, UFH, reasonable-to-good airtightness but not Passive) with an ASHP. My electric infrastructure overlords, UK Power Networks, came out twice to see me and gave me quotes to connect to the network for circa 3k. 

 

As the project has progressed UKPN now say they need £40k+ to connect me, as the local network won't support an ASHP. 

 

Leaving aside the sharpness of this practice for a moment, I am looking at alternative heating methods. 

 

1. Am I right to think I can power the UFH straight from the electric grid? If so, does anyone have an idea of the costs of this heating strategy vs the payback period for an ASHP over its lifetime? I wonder if I will actually be worse off without the ASHP in the end?

 

2. I had not planned to have gas, but could do so if I had to. I presume I would then be looking at a boiler and water tank as per usual, but is there in fact a specific set up required for UFH and gas?

 

3. I couldn't find a way to make solar power work for me when I did my initial research. Partly this was to do with orientation of the plot, but more it was a question of upfront costs vs payback time, affected of course by the end of the grant system. However, a relative of mine now works replacing solar systems and can apparently get me quite a lot of good second hand kit for free, so I may review this option. Is there a good place to go for a reliable solar / heating design?

 

Thanks

 

[J1mbo]

What size is the prospective ASHP? And, what size electricity supply (main fuse) do you have currently?

Edited January 4, 2022 by J1mbo

[ProDave]

WHAT did you tell them about the ASHP you propose to use?  DNO's get very worried about direct on line start heat pumps due to the very large starting current.  As soon as we told SSE that we were using a low power inverter driven heat pump with soft start, all their concerns disappeared.

 

For similar network reasons we were only offered a 12KVA supply, so we accepted that.

 

You could power UFH direct from the grid, and it would consume roughly 3 times as much power as an ASHP, which is not exactly helping the situation and will cost you more and put more load on a creaking infrastructure.

[Tony K]

@J1mbo and @ProDave, thanks for replying.

 

I told UKPN the following, though I was quoting from various places and addressing a subject I have very little knowledge of:

 

'Regarding the required KvA, my electrician informs me that 23KVA will be appropriate, delivering a 100A fuse.

 

In terms of a breakdown:

No landlord supplies.
No street lighting.
No Lifts, Motors, Welders, Cranes or Silos.
No electric vehicle charging point now or in the future (the property is not on the highway and has no off-street parking space).

 

The property will have an Air Source Heat Pump:

 

https://www.nibe.eu/en-gb/products/heat-pumps/air-source-heat-pumps/NIBE-F2040-_-228
 

Max operating current 23A which at 230V is 5.29kW.

Starting current is given as 5A'

[ProDave]

What was the KVA rating of the supply that they originally quoted for?

 

 

[TonyT]

Tell them you have gone for oil.

get the £3k connection and fit the inverter ASHP.

[J1mbo]

or write to your MP...

[Tony K]

12 minutes ago, ProDave said:

What was the KVA rating of the supply that they originally quoted for?

 

 

 

I don't believe they asked for one at that stage. The problem is these details are provided on webforms so I'd have to do some digging to find out if I was even asked the question at the initial stages.

 

Edited January 4, 2022 by Tony K

[Tony K]

25 minutes ago, TonyT said:

Tell them you have gone for oil.

get the £3k connection and fit the inverter ASHP.

 

I wondered about that. Am I not obliged to tell them when I fit an ASHP though?

[TonyT]

Just now, Tony K said:

 

I wondered about that. Am I not obliged to tell them when I fit an ASHP though?

 

Once you have the connection, make sure

your electricity supplier is different from your DNO and crack on

[J1mbo]

Yes it needs DNO approval prior to installation if the post installation maximum demand exceeds 60A (as does a car charger), otherwise notified within 28 days.

 

Maybe request a 60A supply? And then ask for a free upgrade to 100A later...

Edited January 4, 2022 by J1mbo

[Tony K]

32 minutes ago, Tony K said:

 

I don't believe they asked for one at that stage. The problem is these details are provided on webforms so I'd have to do some digging to find out if I was even asked the question at the initial stages.

 

 

@ProDave, Interestingly, I've just found a copy of the webform details I supplied to UKPN - I did tell them I would be using an ASHP and said it was rated at 12KW, but I replied 'Unknown' when asked about how often it would be started in one hour, the starting method and starting current.

 

Is it as simple as me offering a soft start? 

[ProDave]

1 minute ago, Tony K said:

 

@ProDave, Interestingly, I've just found a copy of the webform details I supplied to UKPN - I did tell them I would be using an ASHP and said it was rated at 12KW, but I replied 'Unknown' when asked about how often it would be started in one hour, the starting method and starting current.

 

Is it as simple as me offering a soft start? 

I would quote the power as 5KVA, it's electrical power they are interested in, not heat output power.  Soft star, starting current 5A and no more than 2 starts per hour.

[George]

My installer got Samsung UK to talk to the DNO.

 

They had mistook the 16kW ASHP as the power demand instead of power output. Actual draw was peak 3.8kW - about the same as an electric hob and not much more than a kettle (max 3kW). Also other comments about the inverter and direct start were also clarified, although I believe it mainly came down to an ignorant DNO employee.

 

The specification of the proposed ASHP should be easy enough to get online and that will give the power input / power demand.

 

 

Edited January 4, 2022 by George

[joe90]

I didn’t tell my DNO because I know they would kick off, it was on my planning application but they just gave me am 80amp (fuse) supply for my new build which is fine.

[pdf27]

I'm wondering if they've assumed the heat pump is a 23 kVA one (i.e. 100A draw) through not reading your email correctly. Have they given you a written copy of exactly what they're quoting for?

 

Also, it's possible the network locally would support 60A or 80A, but not 100A - if so you might have to look at your demand calculations more carefully.

Edited January 4, 2022 by pdf27

[ReedRichards]

When my ASHP was retro-fitted my installer applied to the DNO to upgrade my mains fuse from 60 A to 80 A, as 80 A was the largest upgrade they would do for free.  There was a bit of confusion which was resolved after a week or two; the engineer came to do the upgrade and it turned out I already had an 80 A mains fuse, although the case was marked 60 A.  

[ReedRichards]

When my ASHP was retro-fitted my installer applied to the DNO to upgrade my mains fuse from 60 A to 80 A, as 80 A was the largest upgrade they would do for free.  There was a bit of confusion which was resolved after a week or two; the engineer came to do the upgrade and it turned out I already had an 80 A mains fuse, although the case was marked 60 A.

 

Also, I trust that you understand that there are two types of UFH, one that heats using water and the other that heats using electrical wires.   

[Tony K]

14 hours ago, ReedRichards said:

Also, I trust that you understand that there are two types of UFH, one that heats using water and the other that heats using electrical wires.   

 

Yes, I appreciate that. I had of course planned to use electric UFH, but if I end up having to opt for a gas connection then I presume I will have ot use water UFH. That's possibly fine, but isn;t as future-proofed as I hoped an electric UFH system powered by an ASHP would be.

[J1mbo]

18 minutes ago, Tony K said:

 

Yes, I appreciate that. I had of course planned to use electric UFH, but if I end up having to opt for a gas connection then I presume I will have ot use water UFH. That's possibly fine, but isn;t as future-proofed as I hoped an electric UFH system powered by an ASHP would be.

 

Electric UFL is a matt consisting of resistant wire. An ASHP would be connected to wet UFH just the same as would be used with a gas boiler.

[Tony K]

59 minutes ago, J1mbo said:

 

Electric UFL is a matt consisting of resistant wire. An ASHP would be connected to wet UFH just the same as would be used with a gas boiler.

 

Thanks @J1mbo, but is the opposite true? i.e, could I install electric UFH and run it from a gas boiler? I presume certainly not, but I lack expertise!

[J1mbo]

The electric UFH mat is literally just wire in a loop on a mesh former that is connected directly to the electric supply. Power input = power output. It's advantage is simplicity and easy of installation - it can be set in tile adhesive for example with almost no build-up of floor height. However it's very expensive to run as electricity is expensive (currently 21p per kWh, compared to maybe 7p per kWh for gas).

 

A wet system uses plastic pipe looped across the area and typically set in concrete (although other systems are available) and basically behaves like a huge radiator. The heat is applied by anything that can heat the water flowing through it - direct resistance electric heating, ASHP, GSHP, solid fuel boiler or just a plain old gas boiler. The big advantage with wet systems for heat pumps is that the operating temperature is low because the surface area is so large, which typically means the heat pump can work with a higher COP than it would be able to achieve using radiators (since radiators will usually have less surface area overall and therefore the required water temperature would be higher to achieve the same output), and this reduces the electricity demand.

 

However, at least when part of the concrete slab, wet systems provide steady output and this in turn means that they can't offer the quick response heating that a gas boiler with radiators can. Instead the house will be heated 24x7 - which again suits the lower power output of the ASHP (when compared to a gas boiler).

[Tony K]

Thanks all.

 

I am of course pressing my case for UKPN to hook me up to the grid. They knew I had an ASHP from the outset.

 

In the event that I cannot get an ASHP, and given that GSHP is not an option on my site. what is the general view on the next best options? I was originally drawn to an ASHP because it protected me from rising energy bills.

 

I appreciate that I may be asking how long a piece of string is here. 

Edited January 5, 2022 by Tony K

[joth]

54 minutes ago, Tony K said:

In the event that I cannot get an ASHP, and given that GSHP is not an option on my site. what is the general view on the next best options?

 

1/ definitely install "wet" underfloor heating pipes into whatever poured screen/concrete subfloor you are using. This can be powered from anything: direct electricity, electricity via a heat pump, gas, oil, wood burner, aviation fuel, burning stray kittens; any heat source really. Electric mat is a one-trick pony, whereas wet UFH is completely versatile: if it can be used to warm up water, it can be used to drive wet UFH.

2/ If ASHP is impossible mains gas would definitely be next best choice (pending confirmation of the connection price).

 

but I'd definitely push back on UKPN. Have you got a contact to phone? I found them to be extremely helpful once I finally got through to the right person in the projects team. (About different matters: extending a G99 offer period, and repeatedly rearranging power connection schedules due to COVID reasons)

 

A 12kW ASHP sounds large for a 100m2 property. Was it over-sized to allow for faster DHW reheat times? If so you maybe able to downsize it, and increase the UVC tank size (to avoid running out of HW). We have a 160m2 property (EnerPHit, so near-passivehaus) and we could have gone with a 5kW ASHP for heating demand. We upsized to 8kW for DHW reheat times, and I've never seen it draw more than 3kVA from the grid, same as a kettle.

 

 

[Susie]

I’m still at the early stages myself but have been reading up on all my options. As you are only 100m2 have you considered a Willis heater, I had never heard of one but in short it’s like an immersion heater coil plumbed in line with the UFH pipes at the manifold. Like I say it’s new to me so best looking up on this site, quite a few users have one.  I’m considering this for my heating and a sunamp (again look up on here as I did if not familiar) for my DHW.