Comissioning of ASHP

[jfb]

I'm just trying to clarify about what is involved in commissioning an ASHP.

 

I understand that unvented hot water tanks need a G3 sign off.

For the ASHP does commissioning concern correct sizing in planning stage and then what after install?

 

I ask because some have mentioned the ease of DIYing ASHP installs (assuming not going the RHI way). I phoned a plumber who used to be MCS registered and says that while he can do the work he wouldn't be able to do the commissioning and he lets another company do that. What exactly is it that is required? In particular what is actually required if not going the RHI route? What is to stop me having a plumber install the UVC and ASHP without any particular accreditation apart form G3 compliance?

 

thanks

[ProDave]

Simple answer is nothing.

 

I did all my plumbing including the ASHP and the pipework to the UVC then paid the plumber to connect and certify the G3 aspects of the UVC.

 

I suspect anyone not prepared to do the comissioning is simply not prepared to read and digest an installation manual.  It is not very different in terms of plumbing to a system boiler and hot water tank, where it differs is in some of the wiring, and being able to understand the menu's on the ASHP and set some parameters and check it's operation.

[jfb]

1 minute ago, ProDave said:

Simple answer is nothing.

Good to know Dave thanks - I suspected as much.

 

A technical question you might have an answer for Dave - after some advice I have installed 22mm pipework from where the ASHP will go to the UVC (10m run). It is a small place (70m2, well insulated, MVHR) so I was assuming I would be able to do with  5kw ASHP or similar and that 22mm would suffice. After speaking to one company they insist on 28mm pipes but their heat pumps are larger and modulate down.

Have a made a mistake with my pipe sizing or should I be ok?!

[PeterW]

22mm is fine for shorter runs - just make sure the pump is at its highest speed. 
 

In terms of commissioning, one or two of the suppliers need a laptop plugging into the control panels to tune the compensation curves. To be honest, the standard curves are not that bad so it may be a moot point. 
 

The other issue is warranty usually, and some say unless it’s installed by a registered installer you only get one year instead of 3/5/7 etc 

[ProDave]

How long is the 22mm pipe?

 

I had a problem, on first trial, the ASHP tripped with a low flow rate error.  The inbuilt circulating pump in the ASHP could not get high enough water flow rate.  I fixeded it by fitting a second external circulating pump.  In hindsight 28mm pipe would have been a better idea.

[jfb]

9 minutes ago, ProDave said:

How long is the 22mm pipe?

10m