Here is the response from Stiebel-Eltron I have just received. Personally, I don't see a problem with harmonic currents for this one ASHP but maybe the DNO is thinking about the wider problem of several such systems in use and in combination with other harmonic generating loads. Note, though that the 25AS is within limits when put against EN6100011/12 but above those for EN61000 2/3 - I'd need to go read what the latter EN says but I suspect if the DNO says No they mean No.
OP- might you go for a smaller ASHP which is within EN61000 2/3 specification and could achieve the DNO big tick?
The S-E response:
Hello Sir,
I've checked the figures for the harmonics and they are correct.
I think that the DNO has calculated the impact on the local supply and concluded that the heat pump would cause 'flicker'.
The values are within the requirements of EN61000 11 / 12 however they are above EN61000 2 / 3. Basically this means that the client has to pay for an upgrade if he wants to connect this heat pump.
I don't see a way round this.
How about a smaller heat pump that is acceptable to the DNO and retain the boiler as a back up / top up..?
Regards,
John
-----Original Message-----
From:
Sent: 23 October 2018 07:26
To:
Subject: HARMONIC CURRENTS QUESTION FOR SE WPL 25AS
Dear Sir
Thank you for your quick response. I have a supplementary question if I may?
I am helping a client who wants to use the SE 25AS instead of an oil boiler in his home in a village just outside Warwick. He has applied to the Distribution Network Operator(DNO) as required for approval to connect the ASHP since the it is a large relatively constant load.
The response from the DNO talks about reinforcement of the supply to his home at a cost of circa £18000 - which is eye-watering. But the reason the DNO gives for reinforcement is problems/potential problems with harmonic currents, which I think is a little dubious unless they are worried about several ASHP pumps being supplied at the same time.
So my questions is does Steibel-Eltron recognise the figures the DNO has used for harmonic currents for the SE25AS ASHP in their response to my client? I have already asked the client to query the way the third column has been calculated because the negative numbers look odd/wrong to me. Unless I am mistaken there does not seem to me to be a problem with harmonic currents produced by the ASHP 25AS as they are less than the limits in EN61000-3-12.
Regards
D