@crimson That 50 litres of water in the buffer tank, has this been plumbed as the LLH was? Were it plumbed as a two port volumiser, then the loss of space in your airing cupboard / utility area or whatever might be a sacrifice worth making as it would certainly provide the extra volume of water your system may have lacked. Well insulated, it might be a worthwhile move. Regards, Toodles.

Hi @toodles , hope you're keeping well!

It's been plumbed in as a 4 port LLH/volumiser combination.  Much to my annoyance when the specialist wanted it to be a 2 port volumiser just on the return to aid with system volume.

However installers stuck with Grant's requirement with their install pack to have a LLH.  The installer today said he always uses the 5L/other small ones and never had issues.  What's frustrating here is had they actually came and spent time investigating (like I kept asking them to and the builder to) - they may have spotted the pump in the Grant being faulty (and sooner!).

What I'm concerned with now is, a) pump replace - great if that works, but b) now have 50L LLH which could itself cause mixing etc.

Here it is:

(Ignore lack of lagging for now, they're coming back tomorrow/Friday to sort that)

@crimson ☹️ I feel it is time the manufacturers came to their senses and listened to sense concerning LLH v Buffer v Volumiser. In the Q&A presentation that @editor put together, the only indication of any LLH or Buffer Tank benefit did not make it to the presentation as not one invitee would speak up in their favour yet manufacturers still appear to be exercising rear-end protection measures by insisting on their use. Regrets, Toodles.

Posted by: @crimson

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@jamespa be very interested to know your thoughts on this.

A 6L LLH replaced with a 50L one…could that cause more issues?

I'll hopefully have the pump on the Grant ASHP replaced tomorrow, he mentioned they should have just hit a 2:30pm cut off that Grant stated for it to be sent out at 3pm and arrive to installers tomorrow.

Turns out I do have a defrost valve by the Grant ASHP too.………(think different people attending from the installers hasn't helped matters).

I think it's unlikely it will make things worse.

The pump issue is yet another example where a buffer not only degrades performance but also obscures faults.  Without the buffer and auxiliary pump there would have been no flow at all which is easily detected

Posted by: @jamespa

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Posted by: @crimson

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@jamespa be very interested to know your thoughts on this.

A 6L LLH replaced with a 50L one…could that cause more issues?

I'll hopefully have the pump on the Grant ASHP replaced tomorrow, he mentioned they should have just hit a 2:30pm cut off that Grant stated for it to be sent out at 3pm and arrive to installers tomorrow.

Turns out I do have a defrost valve by the Grant ASHP too.………(think different people attending from the installers hasn't helped matters).

I think it's unlikely it will make things worse.

 

That's good to hear.

I truly hope this 10 minute replace of the pump will do the job and I can sign off this project and move on!

Posted by: @crimson

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I'm off in December, and may invest in some kind of heat gun where it's quick and easy to see deltas across rads, and balance the rads again

Definitely worth getting numbers.  It's generally differences that matter so a cheap amazon probe is fine as long as you use tge same one consistently strapped and preferably covered with insulation.  You need to measure when something is happening, ie it's heating, preferably when the problem is evident as well as when it isn't.

Posted by: @jamespa

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Posted by: @crimson

↑

@jamespa be very interested to know your thoughts on this.

A 6L LLH replaced with a 50L one…could that cause more issues?

I'll hopefully have the pump on the Grant ASHP replaced tomorrow, he mentioned they should have just hit a 2:30pm cut off that Grant stated for it to be sent out at 3pm and arrive to installers tomorrow.

Turns out I do have a defrost valve by the Grant ASHP too.………(think different people attending from the installers hasn't helped matters).

I think it's unlikely it will make things worse.

The pump issue is yet another example where a buffer not only degrades performance but also obscures faults.  Without the buffer and auxiliary pump there would have been no flow at all which is easily detected

 

Oh completely, he even said without the hydraulic break either a secondary pump would have taken over or it just would have obviously not been running.  Just madness.

The manual flow setter being blacked out with gunk I guess also hasn't helped (he said he doesn't like manual ones - so why have one in?!!??).

Shortly installer is coming to replace the offending pump &/or the pcb controller (can't remember the term).

1 living room sitting at 19.8C according to a temp heat miser panel.  One of my probes shows 18.7C.  On my list once project complete to configure the heatmiser panels to be -1C as I think the power in them gives them a higher temp than actual.

This is at Grant's default WC with max flow down 5C: 40C max at -3C, 30C min at 20C.

Lets see…

…and it's not the water pump, ramped up to 28l/min - 30l/min, then quite soon after dropped to 20l/min.

Thankfully Grant had the sense to also send an entire replacement PCB, which he seems to be on the phone to them to say can he go ahead and replace that as pump not fixed it.

Dying with anticipation to see the heating just sodding well work!

@Crimon, but the Grant Aerona R32 range has fixed speed pumps with 1,2 or 3 configurable speeds? Coupled with the previously blackened flow setter you mentioned, has anyone isolated the outdoor unit, disconnected the flexible primary hoses, checked and reverse flow power flushed the condenser plate heat exchanger and seen if a load of black gunk is blasted out? The primary circulating pumps are not known [in my experience] to give any issues. Grant Technical's blunderbuss default response is often 'replace the entire PCB', usually out of ignorance, lack of technical competency (on site and/or remote), to correctly diagnose root cause issues. A replacement PCB and new pump won't fix a blockage or restriction on the primary hydronic circuit however. The amount of Grant owners who have had new PCBs is remarkable. That said, they may have upgraded firmware or control burned into them, I dunno...

Posted by: @allyfish

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@Crimon, but the Grant Aerona R32 range has fixed speed pumps with 1,2 or 3 configurable speeds? Coupled with the previously blackened flow setter you mentioned, has anyone isolated the outdoor unit, disconnected the flexible primary hoses, checked and reverse flow power flushed the condenser plate heat exchanger and seen if a load of black gunk is blasted out? The primary circulating pumps are not known [in my experience] to give any issues. Grant Technical's blunderbuss default response is often 'replace the entire PCB', usually out of ignorance, lack of technical competency (on site and/or remote), to correctly diagnose root cause issues. A replacement PCB and new pump won't fix a blockage or restriction on the primary hydronic circuit however. The amount of Grant owners who have had new PCBs is remarkable. That said, they may have upgraded firmware or control burned into them, I dunno...

No idea, they may have done that when did the 50L install, but didn't mention it.

He was saying the primary circulating pump (one bottom right?) - the new one is definitely working better as could barely hear the other one with the panel off and the flow would never get up for long, showed me photos of flow setting not getting past 20l/min.  Bizarrely Grant supplied one with too short a lead, so had to swap that too to the old one (seriously wish didn't have a Grant…).

So now he's telling me the replacement pump has in fact worked.  He's seen it stick to 30l/min on a heating cycle and not seen a short cycle.  Mind you he arrived 1:45, and left at 3pm, so not sure how accurate this is…

…and is "happy" everything should be fine.  So didn't need to do the PCB replacement.  I believe he called Grant and they changed some settings, confirmed Grant pump 2/3 speed and plant room 2/3 speed (flow temps haven't been touched I can see).

To be reconvened in a week or so (colder snap) coming up.

Never know what to think, but will see the proof of the pudding if the room that's always stuck colder hits a decent temp.

At the moment the ASHP I'm having to run hot water for an hour as other half of course has decided needs a shower ASAP (when knew this was happening today).  So I won't really know until 5pm the effect of this.

Am away tonight until Sunday night.  Sunday night I'll go through all the Grant settings to check everything bar the flow being 40 instead of 45C, matches the defaults case he's tried adjusting the delta cut off or something random to mask stuff…