Samsung ASHP Gen 3 issues E911 errors

[Mark Harrison]

As above... We have a Samsung ASHP mated to an Upunor UFH system. E911 errors last winter were resolved by a new flow switch. 

 

The system is about 8-10 years old. The house was a very high spec new build from an insulation POV. 

 

We have had persistent problems/errors the last few weeks that two plumbers have so far been unable to resolve. The ASHP seems to make a full tank of hot water without triggering an error but when the UFH system calls for heat we very quickly get E911 flow error. The flow  switch has been replaced again, both pumps (old Grunfos ones) have been replaced by new Wilo ones and this has pushed the flow rate up over 20 l/m (it was previously around 15) but we still get the same error. The plumber checked the zone valve for the UFH and thinks this is working as it should. Filters have been checked/replaced. 

 

We are at a bit of a loss. The plumber has said the PCB may need replacing but we font want to go the expense of this on a hunch. The call for heat from the UFH only seems to come inconsistently (it should trigger a sun symbol on the Samsung LCD) so the system can run happily producing hot water for a few days but no UFH. If you switch the Samsung control unit off at the mains, when it reboots the sun symbol comes on and triggers the E911 within 15-30 seconds. 

 

And occasionally we get a random E912 error message, just for fun and to mess with our heads! 

 

Could this be some sort of electrical/communication issue between the UFH and the Samsung bits? It's just wierd how it can make hot water with seemingly no dramas. 

 

Any experiences with this or help would be very appreciated! 

[ProDave]

DHW and UFH will only ever operate one at a time, and it is a completely different water circuit for each, so it is quite possible is is not achieving the required flow rate when it is on UFH.  Can you post a picture of your manifold(s)?

 

I had a similar issue with my own ASHP (different make) and the only way to make sense of it was to install an in line flow meter so I could actually see the flow rate being achieved.

[Mark Harrison]

I can try and get a better one later but this is one of them when calling for heat.

[dpmiller]

how many zones and actuators, and is there a separate pump for the UFH?

[ProDave]

I was meaning a full view, to see what pumps, valves, actuators and blending valves you have on and around the manifold(s)

[PeterW]

E911/912 are flow related - I expect either a zone valve is not opening correctly or the manifold valves are getting old and slow if they are the wax cap type. Need a photo of the manifold in its entirety to start with though 

[Mark Harrison]

In between the flow errors the UFH has been working. Thermostats seem to be communicating with actuators OK and these are opening and there is flow through the various zones, just not warm water. There's a manifold upstairs and downstairs. Separate pump for UFH which has just been replaced. 

The heating zone valve in the first pic (top one) has been checked by the plumber (he changed the motor?) and said he thought it was OK. The heating zone valve feels warm to the touch, even with no flow, wheras the hot water one doesnt. I don't know if this is relevant or not.

[Mark Harrison]

Not sure why the photos get rotated when I upload them...🤔🙄

[PeterW]

So there is a single pump pushing into both manifolds from one location..? That will cause poor flow and should follow route of least resistance but in your case I do wonder how it has been piped up. 
 

A warm valve could mean it is stuck - try the metal lever on the side and see if it opens and closes smoothly

[ProDave]

Still need zoomed out photos to see what is between the pipes and the manifolds, where all pumps are, what blending valves etc?  We have little bits of the picture at the moment not the complete picture.

 

The pictures are displaying in their native orientation.  The device you are using to view them and post them probably has the helpful stupid auto rotate function turned on so you don't know they are upside down as your device corrects that and makes you think they are the right way up.

[dpmiller]

yep, looks like we're missing either a blending or bypass valve- unless there's a buffer tank?

[Mark Harrison]

19 minutes ago, PeterW said:

So there is a single pump pushing into both manifolds from one location..? That will cause poor flow and should follow route of least resistance but in your case I do wonder how it has been piped up. 
 

A warm valve could mean it is stuck - try the metal lever on the side and see if it opens and closes smoothly

There's the pump you can see on the first pic plus another one for the UFH. Both are brand new. We've not had a persistent error like this before so I'd assume the setup has been sufficient up til press? The metal lever does go up and down but I'm not sure how 'smooth' it should feel. 

[Mark Harrison]

21 minutes ago, ProDave said:

Still need zoomed out photos to see what is between the pipes and the manifolds, where all pumps are, what blending valves etc?  We have little bits of the picture at the moment not the complete picture.

 

The pictures are displaying in their native orientation.  The device you are using to view them and post them probably has the helpful stupid auto rotate function turned on so you don't know they are upside down as your device corrects that and makes you think they are the right way up.

The manifolds are both it cupboards with no other pumps etc near them that I can see. All the pipework from them just disappears into the floor. The remaining pumps/system is all situated in the garage. I think there's a buffer tank. 

 

This is the other pump in the garage that supplies the UFH loop that has just been replaced 

 

I'll get another picture of the other bits in the garage 

[ProDave]

What me and @PeterW are saying is we can't see how the manifolds are connected.

 

The "proper" way is each manifold has a temperature blending valve and it's own pump to circulate the water around those loops.  It sounds like you don'thave these and one pump directly feeds both manifolds with no local manifold pump or blending valve?

 

If that is the case then if say only one UFH loop is calling for heat, then the flow rate is going to be very restricted.

 

There would normally be an automatic bypass valve so ensure a minimum flow, I can't see that in any of the existing pictures.

[Mark Harrison]

I see what you are saying. Would a blending valve and pump be located close to the manifold? If that's the case, I don't think there is one. 

 

Where's the most likely spot for the bypass valve if there is one?

 

If this was the issue though, would it not have flagged up long ago? The system worked fine all last winter after the flow switch was replaced. 

[PeterW]

7 minutes ago, Mark Harrison said:

I think there's a buffer tank. 

If there is then it’s not a UFH issue and there is a problem elsewhere - a buffer will act as an open circuit

[Mark Harrison]

In this photo, this is literally all there is the cupboard. The water pipes disappear into the wall and I'm not actually sure where they emerge... 🤦‍♂️

[ProDave]

So it looks like there is no automatic bypass valve?  One needs the be connected between flow and return as far from the ASHP as possible but before the motorised valves to ensure there is adequate flow all the time.  The actuators on the manifold will take a couple of minutes to open when first demanded and the heat pump is not going to wait that long before it's minimum flow rate is achieved.

 

If there is a buffer tank then ignore the above.  Post a picture of all the tanks you have?

[Mark Harrison]

Is this a buffer tank?

[Mark Harrison]

Or this red one next to the cylinder?

[ProDave]

No those are both expansion vessels, one for the heating circuit and one for the hot water tank.

 

A buffer tank will be like a small hot water cylinder with some lagging and several pipes connected to it.

[Mark Harrison]

There's a mezzanine in the garage above this stuff. I'll check when I get home later what's up there (my partner has sent these through to me). 

 

Is it possible there's an inherent problem with the actual setup after all these years? The plumber seems to think it's the PCB and is pricing a replacement. 

 

On a more general note, what's the life expectancy (on average) of these systems? It's approaching 10 years and if it needs a lot spending on it I feel like I might be throwing good money after bad. 

[ProDave]

The one thing missing is an automatic bypass valve that would need to go between the ASHP flow and return in the garage before the two motorised valves.

 

I would be very wary of a plumber diagnosing an expensive PCB in a heat pump as the fault.  That sounds too much like fault finding by substitution at the customers expense.

[Mark Harrison]

Thanks Dave. I was a bit afraid of that too. It feels a bit like diagnosis by exclusion at the moment, which I guess is fine up to a point, a couple of new pumps and flow switch don't break the bank but new a PCB on an ageing system feels like a punt at best. 

 

I guess what I'm struggling with is that if the system had an inherent design flaw (lack of bypass valve etc) I'd have expected a multitude of issues before now? Given its age, would it make more sense that something is actually worn out and broken...🤔 

 

Am I right in thinking the call for heat actually goes first to the zone valve in the garage, which then opens and sends a signal to start the heat pump? If this was faulty (even though it's in theory been checked) and wasn't opening fully or quickly enough, it might be enough to trigger the fault? If he's going to replace anything, would this be a more sensible starting point? 

[ProDave]

It is probably an electrician you want to check your system out, not a plumber.

 

There are a number of ways to wire a heating system,buy typically the programmer an room thermostats will call for heat to the manifold control box, that little grey box that the UFH actuators connect to.  When one or more of the UFH zones have been activated, that box will tell the motorised valve for the heating to open, and the feedback contacts from that will call for heat from the ASHP.

 

But there can be a LOT of variations on that, many are heat pump specific.  You you need an electrician capable of working out how it is wired (assuming there is little or no documentation) and then working out if all the bits are actually working properly.