Posted by: @jamespa

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Posted by: @crimson

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16.5 it was 0.33 factor instead of 0.237.

Thats strange.  Then output of convection radiators is always, so far as I am aware, proportional to DT^1.3.  There are minor variations in the exponent, perhaps 0.02 either way of 1.3, but these are obviously just rounding.  The physics is the same after all.

I suppose its possible eskimo have some clever tubework for the airflow, but if so why dont others also do this?

I would personally be suspicious until I had heard a convincing explanation of why eskimo is materially different!

missed this sorry. No idea why, builder and installers contacted them and they stood by their factors. I think I saw them on some programme after the fact and they were going on about size v output etc.

the 0.237 came from the company that has the software that the installers were using, after a lot of prodding to find out what correction factor was being used (the way the heat calc displayed the info really wasnt that clear). Again thats all been checked at least 4x, with the specialist checking also.

Putting the Eskimos against 0.237 ignoring Eskimos own correction factor they still came out ok (had a screenshot of a table I had - 1 living room came out 4% over, 1 7% under - but actually better of the 2 rooms, hall - 92% over).

this was also something we raised at the rad upsize, could Eskimo rads just be even wider to make sure, but they insisted they’d work…

It’s the same story am afraid, they say a fix will work, it doesn’t then blame the Eskimos when they’ve been given opportunities to sort it (they easily could put in 2m wide instead of 1.4m wide ones in 3 spots and a 1.2 in another spot, which i think gave equivalent of adding another 2 radiators).

Posted by: @crimson

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I got them to send me written evidence from Grant for the LLH...

So my comments to this are:

• Protection against low system volume in oversized or zoned radiator systems

can be achieved with a volumiser or bypass valve without system penalty

• Balanced flow rates across mixed emitters (radiators, UFH, etc.)

nonsense, but can be achieved by balancing

• Improved air and dirt separation when combined with appropriate magnetic filtration

This is a function of slowing the flow down ie a larhge tank, plumb the LLH as 2 pipe will still do this

• Compliance with hydraulic separation guidance for heat pump installations

er thats saying - because we (or someone else) says so.

I realise this doesnt help, but you are definitely being given the run around.  I would be tempted to challenge with Grant directly but I also understand that this is taking up too much of your time.

@jamespa 

agreed, your comments are basically the heat specialists responses to Grants mail.

Got to say, wish

A) builder listened to me when said had no confidence in the installers 2023 when they couldn't suggest radiators (only having one brand to recommend seems so bizarre to me). Sending a client an entire catalog of rads without remotely suggesting what would physically fit and what would work was what really got me. And thats after promoting constantly for a good month or so. 

B) wish I didn’t have a Grant unit. Its not very usable as a consumer and the company themselves keep giving conflicting views (I emailed agrant separately and they said a LLH isnt required but a volumiser is…). I’d like a unit that I can see the COP in an app and adjust flow temps, weather curve etc without doing some mad 3 finger key combo and enter random codes. Also the wife hates when I show how to boost the hot water and it has 4 zones, only 1 is the one used. The panels are utter trite. Maybe the panel replacement will help with that but thats a cost I shouldn’t have had to incur if they used something decent in first place. And the hot water cycle running an hour even if its hit hot water temp, meaning the house loses heat for no reason. The list goes on.

Posted by: @crimson

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this was also something we raised at the rad upsize, could Eskimo rads just be even wider to make sure, but they insisted they’d work…

It’s the same story am afraid, they say a fix will work, it doesn’t then blame the Eskimos when they’ve been given opportunities to sort it (they easily could put in 2m wide instead of 1.4m wide ones in 3 spots and a 1.2 in another spot, which i think gave equivalent of adding another 2 radiators).

Well thats good in a way.  Eventually they will be forced to admit that their fixes dont work and actually do what they need to do, if you have that much patience that is!

Im really sorry you are having this much trouble, its shocking how ignorant (and indeed conniving) some parts of the heating industry, indeed the building industry generally, are. 

Sadly you are not alone.  I had a not dissimilar class of experience with 'M&E Consultants' on a job I was responsible for at work.  They had been employed by an architect who knew nothing about anything to do with M&E.  Basically they gave us a load of nonsense both about both heating and electricals, which, had we just believed them without question, would have cost an extra £100,000 on a £1M job.  Fortunately, with a background in physics, I was able to interrogate (and eventually replace) them before they did too much damage.

From what you say you have been careful all along to interrogate your installer and make sure the responsibility rests with them.  I guess its down to your patience whether you persist until they give in (if necessary in the face of legal action) or cut your losses and shell out.  I must confess to doing the latter two years ago with a roofing fiasco that nearly flooded my house on boxing day.  I was angry at the time, but on balance it was probably the right decision for my mental health and relationship!

Posted by: @jamespa

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Posted by: @crimson

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this was also something we raised at the rad upsize, could Eskimo rads just be even wider to make sure, but they insisted they’d work…

It’s the same story am afraid, they say a fix will work, it doesn’t then blame the Eskimos when they’ve been given opportunities to sort it (they easily could put in 2m wide instead of 1.4m wide ones in 3 spots and a 1.2 in another spot, which i think gave equivalent of adding another 2 radiators).

Well thats good in a way.  Eventually they will be forced to admit that their fixes dont work and actually do what they need to do, if you have that much patience that is!

Im really sorry you are having this much trouble, its shocking how ignorant some parts of the heating industry, indeed the building industry generally, are. 

I had a not dissimilar type of experience with 'M&E Consultants' on a job I was responsible for at work.  They had been employed by an architect who knew nothing about anything to do with M&E.  Basically they gave us a load of nonsense both about both heating and electricals, which, had we just believed them without question, would have cost an extra £100,000 on a £1M job.  Fortunately, with a background in physics, I was able to interrogate (and eventually replace) them.

 

Thanks, patience is something I’m trying to maintain (third winter now and I’ve stock piled some wood lol). Thankfully the architect had foresight to hold back more funds to keep this all in play.

I do hope they eventually get put in a corner and have to do something sensible/maybe even say to Grant these LLHs aren’t doing any favours.

@crimson 

I asked Eskimo about their correction factors and received the pretty convincing argument reproduced below.  These would appear to have a genuine advantage over standard steel panel rads.

Thank you for your message and for raising such a valid technical point.

You’re right that many radiators on the market use a generic exponent of n = 1.3 to calculate correction factors. That standard correction factor curve was developed by the large manufacturers of steel panel convector radiators, and reflects the characteristics of those radiators in terms of convection induced by the geometry and thermal conductivity of the heat transfer surface. These designs haven’t changed appreciably since the 1960s and were optimised for even higher water temperatures than those generated by modern gas boilers (the British Standard temperatures pre 1997 were flow/return/ambient 90/70/20°C).

The differences between our aluminium extruded radiators and steel panel radiators is a function of the differing thermal conductivities of steel and aluminium plus the differing geometries of the designs.  Aluminium has a thermal conductivity at least 8 times that of steel alloys. This lower thermal conductivity creates a much steeper temperature gradient along the heating fins for steel than for aluminium. Due to the designs of steel radiators being based upon much higher flow temperatures this effect is increasingly pronounced at low flow temperatures. Below a certain water temperature the steel finned convectors at the back of a panel radiator (what we would refer to as secondary surface) don’t heat up at all and the convective air flow along these convectors (what we might also refer to as a chimney effect) ceases, resulting in the primary surface of the radiator (the flat panel part in direct contact with the water) being the only useful heat transfer surface, hence the much steeper curve to the correction factors.

With our aluminium radiators, we not only benefit from the much higher thermal conductivity, we also designed the geometry of our radiators to optimise them for low flow temperatures, meaning that the extremities of the heating fins are usefully warm even at low flow temperatures and natural convection continues. Consequently, they are highly effective at low flow temps and have a much flatter correction factor curve.

I should note that the correction factor table isn’t linear – if you check out towards the extremes you’ll see your greater deviation, it’s just that the curve is very shallow within this temperature range. If you look at Delta T 35 and Delta T 70, you’ll see that it’s not double for instance.

In terms of testing, all of our radiators were independently tested by Birmingham University at their Tyseley Energy Centre. Whilst we certify to BS EN 442, the standard doesn’t currently include provision for low flow temperatures below the standard Delta T 50C, so the BS EN 442 rating for all radiators only covers the standard Delta T. So, for the Bham Uni tests, we test at 5 points from as low as Delta T 10 and interpolate the curve through those. The tests give an exponent of n = 1.05-1.09.

For me this confirms the need to measure some flow temperatures at input to llh, output of llh,  input to the offending rads and output from offending rads in order to find out what's going on.  Until this is done everything else is pure random swapping without a clue, in the hope of fixing, but for no identifiable reason.  Somewhat similar to the way some car maintenance people work, but with the difference that the car was known to work before something broke which is not the case with your heating.

Installers coming tomorrow. One has messaged messaging not got Fernox F1 but Fernox with antifreeze. What are thoughts on that? He’s happy for me to discuss and research but I will have limited time tomorrow. I’d have rather gone with what Eskimo recommends just to tick that off.

Posted by: @crimson

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not got Fernox F1

My local branch of Screwfix has 18 bottles in stock, it's not exactly rare.

I can't comment on the chemistry.

Posted by: @jamespa

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Posted by: @crimson

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not got Fernox F1

My local branch of Screwfix has 18 bottles in stock, it's not exactly rare.

I can't comment on the chemistry.

They're here today, he brought both:

• Fernox F1
• Fernox Alphi-11 - the one he'd like to use as combination inhibitor/anti-freeze

I've done a brief search and can't find anything indicating a performance hit with Alphi-11 but be great to get another opinion.

Also have reached out to Eskimo radiators on their opinion.

Sorry James - I missed your other post, glad you agree the Eskimos should perform (they do when the ASHP is actually running!).

Saw them on a few TV programmes, (killing me which ones there were though!), where someone needed something to heat a space and rad placement wasn't allowing for massive space, but needed performance.  They really did solve the issue here (if the LLH wasn't there!) - of fitting under the low windows, plus not being mentally wide and having the watt output at delta 16.5.

I still could have had wider rads, as suggested to builders and installers at rad upsize fix but I think builder probably wanted minimal works his end (no replacing skirting etc) and installers ran calcs with specialist and they should be totally fine.

I've raised numerous times to the installers to look at temps pre-LLH/post-LLH and at emitters but they never give it time.

I did at one point have temp probes on tonnes of rads, my memory is naff, but recall seeing about a 1C drop from into LLH and then to first Eskimo on the problematic zone.  However these are cheap probes off Amazon, and the pipework in the plant room is obviously not painted but it is near the Eskimo so I can't say if that's a 'real' drop.

I do know however that have seen a temp drop across the LLH, about 0.5C consistently, sometimes up to 1C.  Upping the pump speed in the plant room reduces that but causes other issues (the noise of running water in the rads is just not something we could live with - and sometimes the pump would make a whining noise which we can hear from the adjacent living room).

I'll give them the chance to see if this 50L LLH/buffer tank has any impact, but not holding much hope.

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 (installers never properly balanced checking deltas, just gradually closed down upstairs along the circuit - again I pointed out to them the Drayton TRV4s actually have a balance under the TRV head, that you can use a Drayton balancing key that shows levels 1-6 so is really good for balancing - I leave the TRV head on Max anyway.  The other valve I think has sod all attenuation so shouldn't be used).

Still a long journey, am hoping it comes to an end soon!

Gone with Fernox Alphi-11, relieves the installers concerns on no anti-freeze (glycol), and Eskimo got back to me saying it's all good.

They've flushed the system, 50L LLH/buffer tank has gone in, tight fit but gets in.

Noted that I think approx they said approx 40L of water in the 5 Eskimo rads, about 12L less than expected, horizontal ones really not much water they noted.

Not sure what was going on with the bleed valves of the smallest horizontal eskimo, they said it drained when opened the 2 bleed valves, but last time an engineer of theirs said couldn't get anything out of it.  We just looked at it and looked like clogged up with teh water lock stuff (that's also around the valve itself) - perhaps a manufacturing error.  That's been poked out anyway.

So another update!

The 50L is in, the plumbers flushed and refilled system.

They ran it for a good couple hours, and……

…the Grant ASHP kept short cycling.  So the living rooms wouldn't hit temp (and it's 16C outside!).

Am so glad they witnessed it first hand.

So…this has finally forced them to fully investigate, and turns out the pump on the actual Grant ASHP is not working well at all.  Showed me on the manual flow setter photos of it on different speeds and it's not hitting the 30 or whatever (can't recall the metric) he'd like.  Basically the pump in the Grant ASHP isn't running at the speed it should.  He did say if there was no hydraulic break (e.g. the LLH…) - the plant room pump would have taken over (the irony).

Seemed frustrated as he felt it wasn't water volume (no idea who to believe as pretty sure they agree water volume…), and is happy to say to the specialist that's not the issue.

He contacted Grant and has put through a warranty claim to get a replacement (hopefully tomorrow, if not Friday) and will come and install.

All I can is happy it's finally (maybe) been narrowed down, but the amount of times people have been here you'd think that would have been spotted.

I asked if then installing the 50L tank was for naught but he says he thinks that may help too as the Eskimos had 30L water in them (got them to confirm) - when it should be around 50L.

I hope if Grant send this pump over and it's installed I magically see high temps, but now bloody concerned got a buffer tank in that won't make things efficient…

@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).