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We are writing to inform you of an unexpected electricity grid issue that requires Derril Water Solar Park and other renewable generators in North Devon to shut down.

We have been notified by the electricity Distribution Network Operator that they are constraining Derril Water Solar Park and other generators in North Devon to prevent potential network overloads. The problem has been triggered by works being carried out at the Transmission Network sub-station at Alverdiscott near Barnstaple. The constraint is unexpected and has been enforced on our solar park and other generators in North Devon with no warning.

The information we have so far from the Network Operators is the curtailment may remain in place through the summer until early September.” Regrets, Toodles.

• Requires constant management, which a non-technical person could not to manage
• Performs defrost even at OAT 15C
• Poor COP during defrosts and cold periods
• Defrosts every 35mins irrespective of evaporator or outside temperature
• Erratic performance, have to turn off to reset
• Split system not suitable for this property
• HP is operating close to its minimum operating performance characteristics
• Short cycling is managed by a SW fix which monitors temperature Flow Temp and waits for a 2C drop before restoring heat.

As Mars would say “Its like managing a patient on life support”.

Today’s activities:

• Returned R32 refrigerant to HP
• Removed Heat Pump and Internal Water Storage unit (125Kg)
• Hole drilled in slab for defrost drainage
• Vaillant HP and Water Storage placed

Pop them below please...

Rather than a 52°, use 35° followed by 45° and finally 52°

Do modern heatpumps already heat the water automatically in this manner, or just whack output temp straight up to the required temp

I guess stop starts would negate any gain. However if the first schedule would normally complete after 50 minutes, simply set the second schedule to start around the 40 to 45 minute mark...

When you read online some say they are overjoyed. You ask how long have they had it and they say a month, that month being April.

Or that they got it for free, yesterday.  It's a £500 Chinese unit with a 1yr warranty.

Maybe it cost £30k so therefore I am entitled to be happy no matter what. ROI of 20yrs by which time it'll be clapped out and need replacing and have £10k spent on servicing and other faults.

So I hit Google with 'how many are happy?' 79 to 94% came the reply which sounds very positive.

I reversed the question and got "15% to 20% of owners report being unhappy or frustrated" which is different, but not far off really.

I was sent a survey to fill in about my new install. I'd never had one.

Are the aforementioned people the ones being asked in the surveys?

I watched a video where an Irish vendor said that their customers complained their electric bills had gone up massively. He then asked about the gas bills and they said 'What gas bill? We don't have one anymore.'

So do you think that some 80% have genuinely had a better system than a new, properly specced and fitted gas combi would have given them? 

I'm not interested in your opinion of your system, you form an extreme minority. What about the majority of ASHP owners? Are they really happy and how would we know? Is there a way of finding out?

I doubt it, but would be really interested to find out.

We are talking to NIBE about replacing it, but there is since a lead time with installers in SE Scotland. At the moment we have no way of heating water.

So over that 10 to 15 years of operation, how much does the power capacity of the heat pump reduce as the components age, degrade and get fouled?

Most articles I've read emphasize the important of sizing the heat-pump as a close as possible to the design heat demand, but presumably that ASHP capacity is when it's brand new, when the fine finned heat exchanger is perfectly clean and the compressor is as tight and well sealed as it will ever be, that 8kW heat pump is 8kW brand new out of the box, but what's it actually capable at year 10 when the heat exchanger is somewhat fouled , fins are coated with a layer of dirt or some areas even somewhat clogged and when the compressor internals are loosening up. 

I'm wondering if there could be an argument that having a bit of a safety margin (how much?) between the design demand and the heat pump capacity, to ensure it's still capable of meeting demand in years 10 or 15 ?