Posted by: @iancalderbank

↑

Posted by: @sunandair

↑

(Unless someone can tell me that a 15 LPM Flow rate through a 19mm bore sensor is the same flow rate through the connected 28mm primaries? Then this is yet another fundamental installer error)

not sure what you mean by installer error, but flow rate as a volume per unit time doesn't change if your pipe gets bigger or smaller as you go along a run. the flow velocity will be different - faster in the smaller pipe.

the smaller meter will may constrain the flow somewhat i.e. contribute to making the overall flow rate slower - But if its not a very long section, the effect of that is usually negligible.

what might be the issue is that the meter may have different accuracy and measuring parameters depending on its size, this is where expertise in metering is needed .

 

What would you like to know?

Most instrumentation systems are selected to operate in their 60% to 70% of Full Scale Deflection (FSD) range under normal operating conditions. Accuracy is normally quoted as a percentage of FSD, so if a flowmeter has an operating range of 0 to 100 lpm, at an accuracy of 1% FSD, then the reading can be expected to be within +/- 1 lpm of the true value.

If this flowmeter is used on a system where the normal flow rate is between 10 lpm and 20 lpm, the actual accuracy of the reading could be between 5% and 10%.

If this flowmeter was replaced with one that has a range of 0 to 25 lpm, at an accuracy of 2% FSD, then the expected accuracy of the reading would be between 2.5% and 5%.

The selection of equipment and range can therefore be quite important.

@derek-m I think your last reply has already answered my query, and thanks for the reply....

It was about the flow meter accuracy if measured in a smaller section of pipe: if I understood your reply correctly you stated the flow rate, when measured in a 20mm internal diam flow sensor, plumbed in to a 32mm diam Primary circuit it would also give the same flow rate at the heat pump where the pipe is 32mm diameter. 

However there were other comments on my post regarding who is the question being asked of? Question being -what do we need to know before installing a heat pump.

since an ordinary householder May have a very different set of concerns and need to know different things than a physics or mathematics specialist who may have a passion for energy conservation for example.

@sunandair apologies, one sometimes assumes a certain level of technical knowledge. The flow rate cannot be anything other than the same because its the same continuous flow of water - no water has been added, none has been taken away . It cannot change. You might get a different reading because the 20mm meter might be rated for different accuracy / flow rates to the 30mm ones, but the actual water flow itself cannot be different.

I note you say you have a sika meter. Is it a samsung install? I ask because the samsung install comes with a sika meter as a standard component. if you want to elaborate on your actual issues please feel free.

can we add this to the list?

- non technical homeowners worried they will have to understand things like flow rates , heat loss calculations and more, that were not a thing they needed to care about with previous heating systems.

however this shouldn't need be the case , if the installer is knowledgable, competent with the install, and gives good aftercare (my 4th bullet )

@iancalderbank 

There’s no need to apologise Ian, I’m an Industrial Designer so I’m used to having to find out about technical matters outside my specific field of expertise. Your first description of flow rate was excellent. To be clear I don’t  have a problem with our existing flow meter performance but I did notice it’s spec was 19mm bore through the mechanism and it was installed in a 28mm pipe so it appeared counter intuitive to measure the flow rate in a smaller pipe section. And even more so when the manufacturers make flow sensor bodies in all the larger pipe sizes.

Sika Meters seem to be the go-to component for many heat pump makes. Ours is a Mitsubishi HP size 8.5kwh.

As an Industrial Designer my design approach is focussed on the person who has to use the equipment, in this case, Primarily the end user and secondary to this might be the installer. This isn’t about pandering to anyone’s whims but it might be as simple as designing the layout of controls or displays in convenient places or making settings and controls user friendly through good ergonomics and aesthetics.

So when I see installations placing the main controller, for example, in a difficult to reach place it screams out The Home Owner is not important!

When the home owner sits down for 3 hours sales pitch and gets offered a Smart Thermostat with their limited knowledge of what that means it repeats to me The Home Owner is not the priority.

If the home owner says they like to feel a warm radiator in the morning when they get up is the specifier tempted to upsize the HeatPump to a larger model and set the flow temperatures higher?

Equally if the design and house spec suggests a smaller heat pump but the unknown existing pipe work may or may not be a problem to circulation is there a temptation to upsize the HeatPump jus to for an assurance?

We had quotes during both, the RHI and the BUS SCHEME and larger heat pumps were specified on several occasions.

So my question is What does A home owner need to know before the sales interview, so that they are better equipped to answer the in depth questions they may be asked. And how do they get that knowledge so they can interpret the choice of options they may be offered.

hope that’s a better explanation Ian

Posted by: @transparent

↑

And which is more realistic...?

• your extrapolations
• my trends
• or the Government's targets?

I think you may know my answer (none of them, hence the suggestion we are both indulging in whatiffery. The government is just plain old deluded).

Rather busy with other things at the moment, but it would be interesting to see what is happening in countries with much higher per 1000 household installation rates.  

Posted by: @sunandair

↑

Not convinced it’s just about cost. My list is worryingly long and still extending into the cold dark night.

I'm sure that's correct for you, but in my conversations with others, they just take one look at the capital cost and decide 'not for me' just yet, and so don't need to do any further investigation (and if they did, they would perhaps end up even more heat pump averse - 'all that cost, and I don't even know it'll work!').  

Posted by: @jamespa

↑

This makes sense, although its not fundamental physics like the Carnot equation so can probably be overcome. @filipe may have a better explanation.

I’ve had another priority: our Mozart Requiem and Coronation Mass concert to focus on -  lots of musical dynamics! Tomorrow the installer is supposed to bring a smaller circulation pump, which may also be temporarily reversed. 

It would be super to be able to explain everything. Who knows what Midea do in their firmware also! Much of physics is based on experiments. I’ve taken my measurements and that’s the way it is. Even the temperature monitoring is nothing more than a tool to see more easily what is happening and move towards better operation. Once achieved I won’t look at it much. Got so much more to do with the time! 80:20 rule in this case. 

Phil

Posted by: @cathoderay

↑

guess.

 

Posted by: @filipe

↑

I’m sure the Octopus approach of targeting standard modern houses with systems that through experience become designed correctly will have a big impact on the transition to renewable technologies. It doesn’t help the older housing stock, but maybe in the big picture that doesn’t matter and price pressures will ease and those houses stay on fossil fuel.

 

 

I'm sorry, I really am (so much so I nearly didn't post this, but it does need to be said) but this doesn't stack up, because most of our housing stock is old, and this proposal (leave the oldies on fossil fuels) will mean that perhaps two thirds of homes will be on that regime, and only one third on heat pumps. I couldn't find UK data, but here is year of build data for England (and I bet the other home nations are similar, perhaps even more heavily weighted to older housing):

We will have to see. Sometimes it is better to start with the easy stuff and get that right. The technology then gets good press and the installer base expands and has a better understanding of what is involved rather than scratching its head when the outcome is not as good as hoped for. My installer is busy doing 2-3 installations/week. If I can help him fix a few problems without taking too much of his time then things may get better. Viessmann are also working on a 2 stage heat pump to be a straight replacement for a gas boiler. 

Phil

Posted by: @filipe

↑

Sometimes it is better to start with the easy stuff and get that right. The technology then gets good press and the installer base expands and has a better understanding of what is involved rather than scratching its head when the outcome is not as good as hoped for. My installer is busy doing 2-3 installations/week.

Phil, don’t you think the industry has already been doing the easy stuff and for long enough already? This energy/carbon transition, we are lead to believe, is an emergency and a necessity for every home owner as quickly as possible.

The reality is that every home owner only needs to do the upgrade only once. So it starts with a moral responsibility. Followed by a trustworthy design and installation. 

Heat pumps work in old brick or timber framed houses if the insulation and draughty doors are dealt with. And a smaller HP will work because controlled heat loss allows it to work. 

Ive been doing planning applications for listed buildings for 30 years and seen the acceptance of good energy conservation measures by most conservation officers and local authorities especially in recent years. There are very few situations where homes cannot be upgraded to create a viable installation site for a heat pump. It does come at a cost but as Ive said, you only have to do this once in a lifetime.

I've read your posts with interest but I think when talking about who should be targeted with heat pump installation it should be all, newer and older housing stock as quickly as possible. 

Posted by: @sunandair

↑

I've read your posts with interest but I think when talking about who should be targeted with heat pump installation it should be all, newer and older housing stock as quickly as possible. 

I agree.  The 'industry' appears to concentrate on making a fast buck whilst protecting its rear end, not rolling out 1.4M heat pumps per year (that's the number of replacement gas boilers fitted each year in the UK).

Of course that's just human nature so needs to be factored into policy making, which is why the government needs to intervene to open up the market to new, more innovative, entrants to the installation sector and make it easier for those who want to fit a heat pump but are prevented by regulation from doing so.

Posted by: @sunandair

↑

Posted by: @filipe

↑

Sometimes it is better to start with the easy stuff and get that right. The technology then gets good press and the installer base expands and has a better understanding of what is involved rather than scratching its head when the outcome is not as good as hoped for. My installer is busy doing 2-3 installations/week.

Phil, don’t you think the industry has already been doing the easy stuff and for long enough already? This energy/carbon transition, we are lead to believe, is an emergency and a necessity for every home owner as quickly as possible.

The reality is that every home owner only needs to do the upgrade only once. So it starts with a moral responsibility. Followed by a trustworthy design and installation. 

Heat pumps work in old brick or timber framed houses if the insulation and draughty doors are dealt with. And a smaller HP will work because controlled heat loss allows it to work. 

Ive been doing planning applications for listed buildings for 30 years and seen the acceptance of good energy conservation measures by most conservation officers and local authorities especially in recent years. There are very few situations where homes cannot be upgraded to create a viable installation site for a heat pump. It does come at a cost but as Ive said, you only have to do this once in a lifetime.

I've read your posts with interest but I think when talking about who should be targeted with heat pump installation it should be all, newer and older housing stock as quickly as possible. 

I agree.  IMO the issue with older housing isn't the wall insulation; loft lagging, windows and doors should fix most and terraced houses are very well insulated on two sides.  It's where to put the ASHP and the HW cylinder.  The 1m boundary rule and the noise regulations need looking at.  And then there are flats. Maybe some creativity around split systems and more use of attics? 

@sunandair @jamespa My installer came to fit a more appropriate size of secondary circulation pump this afternoon (no charge, but he took the industrial pump away). We talked about recruiting plumbers, which he finds difficult. The thinking skills are not high. The industry fits maybe 60k systems pa now and the government wants 600k. Even if only 30% are easy (say of 20M) it would take more than 10years at what looks like an impossibly optimistic rate. 

The purpose of mentioning Octopus was to bring up their model. Nothing stops other businesses doing a full range of house types. I’m not advocating anything and I hope Octopus reduce their limitations on what they take on. 

Anyone researching ASHPs will be put off taking a chance by negative experiences and often contradictory advice/conclusions here. I know many of the members are just wanting to discuss issues, but it is worrying when considering a large investment.

Returning to the downsizing of the circulation pump, I now have a Wilo-Younis Pico which consumes 25W rather than 110W on the minimum speed. It shifts 1.5m3/hour which is the same as the ASHP at its maximum flow.

With only one zone running it ran for an hour at higher output (10kW gradually reducing to over 7kW) albeit at a target temperature of 48c before stopping the compressor. The impression I had was the ASHP was seeing a higher load even with one zone of 8 radiators. I don’t particularly want the heat (it reached 21.6c) so enough for today. I will see what it does tomorrow at 30c flow target when it has its service (£115+ vat). I still managed to export 23kWhs to the grid with an extra 4kWhs for heating. The Flux tariff pays very nicely.

My installer said he has learned a lesson about flow rate through the plate heat exchanger. We need more data before deciding whether counterflow is needed with this heat exchanger. Basically the secondary delta T may need more time to reduce so the secondary output temperature can rise more (perhaps). The plate length/area is fixed.  More plates may help, but it has 36 and 40 is the limit. Pump reversal is only suitable on a short term basis because the zone valves may snap closed with reverse flow.

Phil

My impression with Octopus after emails with them about getting a survey done (I don’t fit the bill so have looked locally instead) is that they were starting with (relatively) straightforward installs and as they build up their installer base and knowledge base within that group then they’ll broaden their horizons.