Help required wiring my ASHP/UFH

[Pete]

38 minutes ago, joe90 said:

I have to go away for 48hrs again so will try this when I return. Thanks chaps.

For Re-hab?

[joe90]

Sorry, just re read all above @Nickfromwales is right (as  always!) I have a two way diverter valve .(it just diverts the wrong bloody way?)

[joe90]

1 minute ago, Pete said:

For Re-hab?

 

A stiff drink at least.

[joe90]

@Nickfromwales has confirmed that a diverter valve should sit at heating normally and on DHW demand power up. This is what my ASHP diagrams show but the valve I have (which I cannot reverse the head on) is the opposite. Am I the only one to have a diverter valve that does this?. I am going to drain it down and reverse the valve, should cure the problem (at last). Sorry for the long thread I just could not get my head around it.

[Onoff]

1 hour ago, joe90 said:

@Nickfromwales has confirmed that a diverter valve should sit at heating normally and on DHW demand power up. This is what my ASHP diagrams show but the valve I have (which I cannot reverse the head on) is the opposite. Am I the only one to have a diverter valve that does this?. I am going to drain it down and reverse the valve, should cure the problem (at last). Sorry for the long thread I just could not get my head around it.

 

Been a great example of tenacity and forum help imo. I wonder how many ASHP are out there, not working and giving them a bad name over something like this? 

[Nickfromwales]

Hold that compliment.  

 

 

Replied to joe last night with one eye half open.

 

[Nickfromwales]

@joe90

With both eyes open it reads that B aka DHW is the parked position of the valve. 

I’ll get my coat. 

It’s the mid position that parks in the heating position for pump overrun. 

 

[ProDave]

Would in not be a whole lot simpler if instead of labelling them A and B or DHW / Heating, they just labelled them NO (normally open) and NC (normally closed) like a relay?

[newhome]

1 hour ago, Onoff said:

 

Been a great example of tenacity and forum help imo. I wonder how many ASHP are out there, not working and giving them a bad name over something like this? 

 

Given the 165 pages on this thread (you will need a translator!) I imagine it’s a relatively common problem. 

 

https://forum.softpedia.com/topic/528151-pompe-caldura-aer-aer-aer-apa/page__setlanguage__1__langurlbits__topic/528151-pompe-caldura-aer-aer-aer-apa/__langid__1

 

 

[Nickfromwales]

3 hours ago, ProDave said:

Would in not be a whole lot simpler if instead of labelling them A and B or DHW / Heating, they just labelled them NO (normally open) and NC (normally closed) like a relay?

In fairness, it does come with pretty clear instructions. I was just to tired to think last night.  

[Ed Davies]

Sorry if this derails the thread a bit but I'm intrigued as to why (so emphatically) these valves mustn't be put in the return pipework. Is it just that the pressure in the wrong direction (from A or B to AB) would overcome the motor/spring?

[Jeremy Harris]

3 minutes ago, Ed Davies said:

Sorry if this derails the thread a bit but I'm intrigued as to why (so emphatically) these valves mustn't be put in the return pipework. Is it just that the pressure in the wrong direction (from A or B to AB) would overcome the motor/spring?

 

I have a feeling it may be to do with the way that the internal flap is oriented.  It perhaps doesn't like to see flow towards it's non-hinged edge?

 

I fitted motorised ball valves, as they seemed to me to be a better solution, not least because they don't consume any power in either position. 

[Onoff]

6 minutes ago, Ed Davies said:

Sorry if this derails the thread a bit but I'm intrigued as to why (so emphatically) these valves mustn't be put in the return pipework. Is it just that the pressure in the wrong direction (from A or B to AB) would overcome the motor/spring?

 

You WANT/NEED an open return line on any pumped system surely? Say the valve failed shut, where's the pressure going to go?

[Ed Davies]

3 minutes ago, JSHarris said:

I have a feeling it may be to do with the way that the internal flap is oriented.

 

Yep, that's the sort of thing I was trying to visualize. Pressure from AB would help hold it in place perhaps whereas from A or B it would push it towards the central position.

 

3 minutes ago, Onoff said:

You WANT/NEED an open return line on any pumped system surely? Say the valve failed shut, where's the pressure going to go?

 

Can't see why it makes a difference whether it's on the flow or return side for that - either way the pump's pushing into a dead end, just one with a smaller volume if the stuck valve is on the flow side. That's assuming that the pump is just before the exchanger in the heat pump.

[PeterW]

Pump on the AB side drawing down would pull against the seal on the valve - so if it’s on A then it could pull both A and B. They use the slight water pressure to hold the seals closed. 

[joe90]

9 hours ago, Nickfromwales said:

With both eyes open it reads that B aka DHW is the parked position of the valve. 

 

Exactly, which is why my system is ass about face, my heat pump energises the valve when calling for DHW. Yet the instructions on the heat pump wiring and valve instructions say the opposite. I still can’t believe I am the only one to have had this problem.

 

many thanks you guys ?

 

 

[joe90]

Right, drained it down and took the diverter valve off and confirmed that in parked mode water flows from AB to B. Which should be heating, when powered up water flows from AB to A (DHW). This is as per @Gav_P pic above but not as the drawing I got with the valve.

 

NOTE, I noticed that when using the manual override on the valve it only opens the valve halfway like a mid position valve!!! This must be for drain down only and not to manually operate the valve, this is why when trying the valve I was confused as both pipes got hot, it can only be tested by electrical energising.

[ProDave]

I think the lesson here is don't just believe the instructions, actually LOOK at the thing and see if it really behaves as it should.

[joe90]

I now have 20, 20 hindsight , I also have ordered a computherm room stat (that @JSHarris recommended as I can’t be arsed to wire in a relay to deal with the Wunda stat that blew my main ASHP board ?

Edited November 12, 2018 by joe90

[Gav_P]

3 hours ago, joe90 said:

I noticed that when using the manual override on the valve it only opens the valve halfway like a mid position valve!!! This must be for drain down only and not to manually operate the valve, this is why when trying the valve I was confused as both pipes got hot, it can only be tested by electrical energising.

I guess that’s so you can have both heating and hot water in the event of the motor on the valve failing. 

 

The good news is you will now have a fully(and correctly) functioning heating and DHW system!! Time to celebrate! ??

[joe90]

9 minutes ago, Gav_P said:

Time to celebrate! ??

 

Thanks mate, I am chuffed like you after our problems, see my other new thread!!!!

[Nickfromwales]

16 hours ago, Gav_P said:

I guess that’s so you can have both heating and hot water in the event of the motor on the valve failing. 

Its only meant for commissioning  Its for filling and draining the system when powered down. Where a motorised valve and cylinder stat are inclusive of the system design, you should never run a system knowingly bypassing the safety features ( the cylinder stat ). Also, for an ASHP installation, each flow ( DHW or Heating ) command different flow temps so another reason not to 'cheat' it. 

[Gav_P]

Phah. Safety features are for wimps!

[Nickfromwales]

19 hours ago, Gav_P said:

Phah. Safety features are for wimps!

 

"anyone seen my UVC ?"

 

[joe90]

On 12/11/2018 at 14:30, joe90 said:

I now have 20, 20 hindsight , I also have ordered a computherm room stat (that @JSHarris recommended as I can’t be arsed to wire in a relay to deal with the Wunda stat that blew my main ASHP board ?

 

Right, my new computherm stat has arrived, but, (am I getting OCD ?), it’s ugly, if it was in a cupboard I would not mind but it’s eye level in the hallway and I like the look of the Wunda stat (that blew up my ASHP main board).    SO, I have taken the Wunda stat apart to see if I can make it a dry contact operation and I think I can, ( plus the computherm came with no instructions on fitting or programming???), and boy do I need instructions ?. Wish me luck.

Edited November 16, 2018 by joe90