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Noted. As I say the Valiant installation manual I have does not require an RCD, but does specify the type if one is fitted.
I would say that the document above could be read either way however if you read it as RCD mandatory then a fuse is also mandatory and hardly anyone is going to fit one of those. Thus I would personally refer to the installation manual for clarification.
This was a bit of a nightmare when I discussing my install with the provider. However, the install manual also stated that I need this:
2024 build bungalow, Southern England, 179 m2, 14w/m2 Underfloor heating, fully open
Vaillant aroTHERM plus 3.5kW
50 litre volumiser
3.6KW solar panels
Noted. As I say the Valiant installation manual I have does not require an RCD, but does specify the type if one is fitted.
I would say that the document above could be read either way however if you read it as RCD mandatory then a fuse is also mandatory and hardly anyone is going to fit one of those. Thus I would personally refer to the installation manual for clarification.
This was a bit of a nightmare when I discussing my install with the provider. However, the install manual also stated that I need this:
Same as I quoted, no requirement for an RCD to be fitted but if one is fitted then it must be of a specific type. I think that's very clear and also entirely logical.
Not sure why they use the word 'fuse'. Most installations will use MCBs these days. Maybe it's a translation from the German or Czech.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
@transparent. It looks from the picture posted earlier as if this RCD is fed from the main cu. That being the case perhaps there is an MCB in series there
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
There is NO MCB in the main consumer unit for the heat pump.
So I'd be interested to know where the feed to the new CU is supplied from... ... and what size cable it has between the two units.
Sorry missed that. It's pretty obvious from the photo that this RCD is fed from the main cu, but if there is no MCB then, as you say, what protects the cable?
Hager CDB540HP is a Residual Current Circuit Breaker.
Here's the English text in the Installation Manual. It measures current which leaks to earth.
It needs an MCB in series to provide over-current protection.
The current rating of the MCB is determined by the cable-size which supplies the Heat Pump. Do you know what that is?
I don't know specifically but based on physical size, it looks like standard twin and earth that would be used on a 13 Amp socket. This is the feed from the CU to the Heat Pump.
I don't understand why the electrician working for @trebor12345 chose this particular Hager unit.
Based on what I was told and read, because Vaillant and Hager collaborated to design this heatpump RCCB model. So marketing appears to have used that as a springboard. Most of the electricians seem to know the Hager solution as a way to reduce nuisance tripping, etc.
We are planning to get a Vaillant so most of the installers that estimated for us seemed aware of this.
The situation of requiring such a specific RCCB is hopefully transitional. Vaillant would probably want to remove this complication by:
designing out the possibility of DC currents;
or incorporating a suitable circuit protection device in their unit.
The current Vaiilant manual says the same as mine, IE it specifies the type of RCD if an RCD is fitted, but does not specify that an RCD must be fitted. That latter decision is, by implication, left to the installer/local regs.
I had a look at the German language documentation for the Arotherm Pro (no British version available).
It only includes a generic mention that implies an RCD/RCCB is not mandatory:
"If prescribed for the installation location, check whether an RCD has been installed"
I also did a deep search for any references to any special type of RCD but could not find anything for the Pro (e.g. VWL 75/7.1 for the 7kw model). Perhaps this new model is the first that no longer needs DC capable residual current circuit breakers.
This post was modified 4 weeks ago 2 times by Batpred
8kW Solis S6-EH1P8K-L-PLUS hybrid inverter; G99: 8kw export; 16kWh Seplos Fogstar battery; Ohme Home Pro EV charger; 100Amp head, HA lab on mini PC
I don't understand why the electrician working for @trebor12345 chose this particular Hager unit.
The electrician was an employee of the company that performed the HP design and installation. As part of the design process I felt it was a mandatory requirement.
2024 build bungalow, Southern England, 179 m2, 14w/m2 Underfloor heating, fully open
Vaillant aroTHERM plus 3.5kW
50 litre volumiser
3.6KW solar panels
?x79161
