joe90

Jeremy, you are a star (again). I have the 713 and looking at the connection tabs on the photo below I was confused by the writing and rang Wunda tech services and they told me the manufacturer printed them wrong and it was an isolated switch contact. Just checked it and yes when the stat calls for heat it produces 240v across n1 - l1. i suppose I will have to drive a relay with this to give me switch contacts to switch the ASHP call to heat? Luckily I have just bought two mains relays (one fir the MVHR using a humidistat). I just hope applying mains across the 12v supply in the ASHP has not done any damage.?

Builders have turned up to erect the conservatory, when I have got them settled in ( making tea!) I will start by checking everything and run more tests. watch this space.........

Brain freeze, yes Dave, RCBO. Weird because if I disconnect the switch wires (dry contact) on the room stat it does not happen, when the switch wires are connected a flash appears in the back of the stat and the RCBO trips when the stat calls for heat, the 3 amp fuse does not blow so I guess it’s an earth fault, but these low voltage wires are not connected to the mains. Tomorrow I will see if either the live or neutral going to the stat connects to the switch wires in the stat, which I think would be an internal fault in the stat.

I don’t think it is a flow problem because (if I understand it correctly) I have an external pump and the three way valve is normally parked at “heating” so there is no valve waiting to open when the ASHP starts up. Again I say it’s the MCBO in the fuse board that’s tripping showing a fault in the wiring which occurs when the Wunda room stat calls for heat. I will look at this after a good night kip (I hope ?).

Will try in the morning Dave. As an aside, the house is now at 23’ (UFH working on buffer tank heated by immersion) the TRV on the manifold is set to frost but the water temp going into the floor is 24’. Er indoors says it is “just right” whereas I am sweltering. I need to get this working properly otherwise i will melt.

I will have a look in the morning. But, when it trips it is the MCBO in the fuse board for the spur that feeds both the room stat and DHW timer. On removing the stat from the wall there is a flash and spark from inside the room stat!!! I am guessing the room stat may be faulty, if I take the switch wires off the stat and short them together there is not a problem (apart from it not doing what it is supposed to. If it was the flow that was a problem I am guessing the ASHP would just shut itself down. Glass of wine ? and TV for me. to be continued.........

Its the Wunda room stat. Just tested it all and no apparent wiring problems. Connected it again and as soon as the stat calls for heat the consumer MCBO for that ring that the room stat and timer are on trips . Fast losing the will to live ?

Yes in pencil, will do it properly and post. see above post has been added to. GGGGRRRRRR

Right (big Intake of breath) wired in the Wunda room stat, timer for heating and switched it on, pump ran for a short while then tripped out an adjoining cct ?, tried again, same thing (scratching head). Turns out my builder who is putting up my new conservatory has a faulty chop saw and it’s that tripping out the same cct as the power to the room stat and timer. Perhaps I will provide an additional cct for these later. Anyhow, lent them my chop saw and the pump is still running for about 10 seconds then switching off, it tries again in about 30 seconds. I think I have seen this described on the forum somewhere but can’t find it. My worry is having bought my ASHP from Ebay like @ProDave I end up with the same problem as he did ? “SIT REP” after about 10 attempts the ASHP is running, just hope it produces heat??? watch this space.............. AAARRRRGGGGGGGHHHHH. cct still tripping ( ringmain feeding timer and room stat) trips after about 6 seconds, found it’s the Wunda room stat, large spark from inside on tripping. Will be calling them first thing. Need to contact builder and apologies for blaming his chop saw?

Technically I did not mention the ASHP to either the planners or the DNO although the plans fir planning had it on (very small). I had heard that DNO,s don’t like ASHP and sometimes want a bigger supply but I have read that modern ASHP,s draw less current than electric showers!!

I fitted a new boiler for a customer (Gas man did the Gas work and signed it off). But the customer declined a power flush (tight old git) and he called me back (not the gas guy) 2 months later because it stopped working, I got the gas guy to find the problem and a heat exchanger was completely blocked and had to be renewed, customer was furious but Gas guy said I was right telling him a power flush was a good idea, pay up (up front) for the repair or it didn’t get done. He also (like me) recommended a magnaclean.

Yup, tests ok. Thanks Dave, good idea ?

It’s no wonder I get confused, just started to wire the Wunda room stat and thought they had sent the wrong one, should be dry contacts but appears to show electric underfloor heating element (my electric ensuite UFH is like this). Called Wunda technical support and they tell me the manufacturer got it wrong and they assure me it’s dry contacts inside ?

Jeremy, give me a call, I am more than willing to come and give you a hand, I would have helped with getting the new one in if I had known, don’t risk damaging your house (or yourself for that matter), it’s not worth it. ?

Ah, I have not got the programmable stat that closes 3 to 6 as I was going to use the command unit as the stat, if I do this I think I need to change the parameter 100 from standard no1 to 4? (System type a2w. Nui as stat). I do have a Wunda room stat that I was going to use and have wired ready for it in the Hallway, so not sure which is best (command unit is in the cloakroom next to the plant cupboard.) when it stops raining I will get the cover off and check voltages.

Got the underfloor heating working from a backup immersion In the buffer tank, TRV on the manifold on frost and water temp into the manifold 24’ ??? Which is ok, er indoors happy with warm feet. Wired up the ASHP and Nothing, Flashing LED indicates all ok, Need to go through all the wiring and check all is ok. Can’t find a commissioning doc on the way to start it fir the first time, is there anything I should be looking for (going shopping for food as my brain hurts).

If it helps here are the default values from my carrier unit.

My carrier unit rebadged Kingspan has cooling, set by the command unit and a link removed in the wiring. Not planning to use it at the moment but an option for the future if required.

Thanks Jeremy, I will get the ASHP up and running and see how it goes, if necessary I will get one of those balancing valves, they do seem very good.

That was part of my planning fiasco, the council deemed part of our garden as “agricultural “ and I asked them how they came to this decision as all maps of the area clearly defined our garden and the field next door that we also own. They tried to tell me google earth was to blame but I proved there was no hedge fence or ditch as boundary and also discovered that family members could sign a letter stating that in the last “X” years they had used that area as garden (luckily the plot has been in the same family for 50 years). The council dropped their argument!.

Right , UFH working (temporarily using immersion in the buffer and pump on permenantly), nice warm floor but a few questions. The TRV on the manifold has a curly wire to a probe that fits in a socket on the top of the manifold (as below) the probe is a loose fit in the pocket, is this right? Will it register the correct temp if not a friction fit? Also the TRV when set at its lowest ( * ) the top rail temp shows as 25”. Is there a better TRV (I think PeterW was getting one). When I contacted Wunda about this they did not show any interest (don’t think they understand passive house principle).

Ah yes, oops thanks Jeremy.

Yup, all up and working, whisper quiet on 1 and blowing a gale on 4! Even 2 is quite powerful. I have not balanced the system yet just restricted the close room pipes a bit at the manifold. I also have to wire in a humidistat with a relay as this is the way I wanted to control bathroom steam etc (wish I had thought to wire a boost button in the kitchen like Dave.

Well done, as others have said utilities are a pain to deal with (ask me how I know?).

Star man, just checked and mine is command 157. Slightly different, 0 = always off. 1 = on/off depending by EHS on/off status. 2 = always on. I thought the external heat source was to stop defrosting? So perhaps 1 = pump fir external warm water to defrost it?? . So 2 will Work which is the default. i am confused tho as command 155 indicates the main water pump is set to depend on EHS being on (I prefer woodwork ?)