Samsung ashp flow problems

[S7evo]

Hi all. First post, appreciate any guidance ?

 

We have a Samsung Ashp which provides all our hot water (via immersion when needed) and underfloor heating.

 

We continually get e911 flow issues, and have tested and swapped flow switches to no avail. Having read the some documents for months as can't get a plumber who wants to deal with it, I think it's plumbed incorrectly which may be throwing the flow issues.

 

The switch is on the wrong side of the flow meter, and there should be (but isn't) at least 150mm before any bend or fitting either side, I think.

 

Can anyone clarify that I am correct, or barking up the wrong tree? Setup image attached.

 

 

Thanks

[Ferdinand]

Welcome to the forum.

 

On this subject I am just the annoying voice in the Passive Cat Flap, however.

[PeterW]

Hi

 

Looks fine to me - there is 150mm either side of that before the bends. Where is the flow meter..?? (picture is a bit dark)

 

Also, is that the only pump you have in the system..? Is there a three way valve anywhere, and is there a bypass valve...??

[Jeremy Harris]

Welcome @S7evo.

 

It's not uncommon to get low flow rate errors with an ASHP installation.  We had the same initially, due to flow restrictions caused by a valve being slow to open, and I think others have reported much the same with other makes of heat pump (ours is a Glowworm badged Carrier).

 

I think your pipe layout looks OK, and suspect that the issue may be with either a restriction somewhere (like a slow to operate valve, perhaps) or with there not being enough pumping power.  I had to play with the speed on the pump in our unit to get it to work reliably without throwing a flow error, for example.

 

I fitted a bypass valve to finally fix our low flow errors, but a better solution might have been to fit a low loss header instead.  Next time I drain our system down I'll probably remove the bypass valve and just fit a low loss header, just because that will work with no moving parts or adjustment.

[S7evo]

4 hours ago, PeterW said:

Hi

 

Looks fine to me - there is 150mm either side of that before the bends. Where is the flow meter..?? (picture is a bit dark)

 

Also, is that the only pump you have in the system..? Is there a three way valve anywhere, and is there a bypass valve...??

Thanks for feedback Peter. 

 

Flow meter is to the left of the green circled switch. There is less than 20mm between the flow meter fitting and the shut-off valve. To the left before the elbow there is about 100mm after the flow meter fitting. What I do notice is that closing the shut-of valve does boost flow above 20l/m. Unsure if this is a faulty valve, or just the turbulence makes it appear the water is travelling faster? Still get the flow rate code after a few minutes regardless...

 

System has 3 pumps:

• 1- from the ashp to the house (shown) which can feed the low loss header or cylinder.
• 2 from the low loss header to the upstairs rads
• 3 from the low loss header to the underfloor system

All pumps are reasonably powerful (i think) at 6 - 7.5m head. have them all set to max, have ensured the divert valves are fully open or closed but flow doesn't increase or decrease.. not sure we have a bypass valve installed.

 

Any more thoughts?

 

Appreciate taking time to comment.

Edited October 14, 2019 by S7evo

[S7evo]

13 minutes ago, S7evo said:

Thanks for feedback Peter. 

 

Flow meter is to the left of the green circled switch. There is less than 20mm between the flow meter fitting and the shut-off valve. To the left before the elbow there is about 100mm after the flow meter fitting. What I do notice is that closing the shut-of valve does boost flow above 20l/m. Unsure if this is a faulty valve, or just the turbulence makes it appear the water is travelling faster? Still get the flow rate code after a few minutes regardless...

 

System has 3 pumps:

• 1- from the ashp to the house (shown) which can feed the low loss header or cylinder.
• 2 from the low loss header to the upstairs rads
• 3 from the low loss header to the underfloor system

All pumps are reasonably powerful (i think) at 6 - 7.5m head. have them all set to max, have ensured the divert valves are fully open or closed but flow doesn't increase or decrease.. not sure we have a bypass valve installed.

 

Any more thoughts?

 

Appreciate taking time to comment.

Double checked, we do indeed have a bypass valve on the upstairs heating circuit.

[Jeremy Harris]

31 minutes ago, S7evo said:

Double checked, we do indeed have a bypass valve on the upstairs heating circuit.

 

 

Is it an adjustable one?

 

If so, you could try reducing the opening pressure a bit, as that may allow it to bypass and increase the flow rate.  I found I needed to play around with the setting on our bypass valve a fair bit.  Set it too low and it just bypasses all the time, increasing the return temperature.  Setting it too high meant it didn't open when the pressure rose, so the ASHP flagged a flow rate error.

[ProDave]

I had exactly the same issue with my (LG) ASHP when I installed it.  At least Samsung tell you what the flow rate should be, LG didn't, I had to phone them and ask.

 

What I did was install a flow meter in line with the pipework. That then showed me the flow rate was indeed less than it needed to be.

 

I solved it by fitting a second circulating pump. My LG ASHP has a Wilo pump similar to yours built in. I now also have a Grundfoss pump half way along the flow pipe, and having two pumps running together solved the problem.

 

Alternatively change that Wilo for something with a greater flow rate. Although I like Wilo pumps because they are quite, they are not the most powerful.

 

But before you do that, does it always trip under a certain set of circumstances?  e.g when you first turn the heating on, or when it switches from heating to hot water?  If that is the case it could be a motorised valve taking too long to open and the bypass not giving enough flow.

[S7evo]

2 hours ago, JSHarris said:

 

 

Is it an adjustable one?

 

If so, you could try reducing the opening pressure a bit, as that may allow it to bypass and increase the flow rate.  I found I needed to play around with the setting on our bypass valve a fair bit.  Set it too low and it just bypasses all the time, increasing the return temperature.  Setting it too high meant it didn't open when the pressure rose, so the ASHP flagged a flow rate error.

@JSHarris yes it is adjustable but doesn't make a difference I can see ?.

 

Trips out in all scenarios i.e calling for underfloor, calling for hw, calling for upstairs rads. All together, independently, always trips 

 

Thanks

[ProDave]

Before we go any further:

 

Has this EVER worked properly?  i.e. it used to work properly but now it is giving this flow error?  OR is it a new installation and it has always given this flow error right from the first time it was turned on?

 

If the latter who installed it and what have they said?

[S7evo]

1 hour ago, ProDave said:

I had exactly the same issue with my (LG) ASHP when I installed it.  At least Samsung tell you what the flow rate should be, LG didn't, I had to phone them and ask.

 

What I did was install a flow meter in line with the pipework. That then showed me the flow rate was indeed less than it needed to be.

 

I solved it by fitting a second circulating pump. My LG ASHP has a Wilo pump similar to yours built in. I now also have a Grundfoss pump half way along the flow pipe, and having two pumps running together solved the problem.

 

Alternatively change that Wilo for something with a greater flow rate. Although I like Wilo pumps because they are quite, they are not the most powerful.

 

But before you do that, does it always trip under a certain set of circumstances?  e.g when you first turn the heating on, or when it switches from heating to hot water?  If that is the case it could be a motorised valve taking too long to open and the bypass not giving enough flow.

@ProDave Was intermittently tripping, would stay on all month then find it tripped when we come home, sometimes trip after an hour then be fine for ages. Now tripping constant a few minutes after turned on, before any valves are opened, hw/ch requested.

 

Pump is a 7.5m head pump, so should be sufficient?? 

 

 

[S7evo]

2 minutes ago, ProDave said:

Before we go any further:

 

Has this EVER worked properly?  i.e. it used to work properly but now it is giving this flow error?  OR is it a new installation and it has always given this flow error right from the first time it was turned on?

 

If the latter who installed it and what have they said?

 

Worked since 2016 until recently. Was a new build by a small developer.

 

First fault we had was flow when there shouldn't be back in Feb 2019. Been fine since then, now the opposite fault, not enough flow. Only thing that changed was the addition of a new flow switch and shut off valve.

 

 

Really appreciate the help.

[ProDave]

The "head" that a pump will work to, does not determine the flow rate directly.

 

Our LG heat pump only needed 10L/min minimum and I could not achieve that with a single Wilo pump.  It all depends on your pipework, and in my case it was simply too long and / or had too many bends, so I could not get the flow rate needed.

 

Have you tried adjusting the speed on the pump?

 

Looking again at your picture, you already have a flow meter in place.  What is the flow meter reading showing?  or if you don't know how to read it, post a macro photograph of the flow meter.  It is the bit to the left of the flow switch with a little glass window to see the position of a plunger that moves according to the flow it is measuring.

[S7evo]

3 minutes ago, ProDave said:

The "head" that a pump will work to, does not determine the flow rate directly.

 

Our LG heat pump only needed 10L/min minimum and I could not achieve that with a single Wilo pump.  It all depends on your pipework, and in my case it was simply too long and / or had too many bends, so I could not get the flow rate needed.

 

Have you tried adjusting the speed on the pump?

 

Looking again at your picture, you already have a flow meter in place.  What is the flow meter reading showing?  or if you don't know how to read it, post a macro photograph of the flow meter.  It is the bit to the left of the flow switch with a little glass window to see the position of a plunger that moves according to the flow it is measuring.

@ProDave flow is reading above 14l/m. Pumps (all 3) are flat out

 

Noted ref the pump head. Will establish the current flow rate of the wilo. It may be failing perhaps.

[ProDave]

Then perhaps the flow switch is playing up?  But assuming a linear scale you have about 17l/min, which given the accuracy of the flow meter and the flow switch, is marginal for a 16L/min requirement.

 

Turn the heating off. Shut off the isolators either side and you should be able to unscrew the top of the flow switch and check for debris, sticking mechanism etc.  It will be interesting to see what is inside i.e. what sort of flow switch.

 

P.S. you desperately need some pipe insulation on that lot. You must be wasting a lot of heat there and that cupboard will be roasting.

[S7evo]

So latest update, hoping I'm not about to jinx the issue... All working although flow appears low but not tripping the sensors ?

 

The flow switch was a rectangular type paddle, looks like it had a small part broken off (maybe inside the pipe, restricting flow?) so ordering a new one.

 

Pipework was altered by placing the flow switch further away, i.e. to the left of the inspection window. Switch is rattling like hell and no adjustment of the dial makes a difference.. will pop a new one in and assess if it still happens.

 

Pump was switched out to test if the existing was failing, but flow was similar. So that leaves a blockage potentially?. Nothing in the filter that's obvious..

 

Will update if we find anything more.

 

Thanks for the suggestions and help. Currently in a warm home ??