Posted by: @mattcPosted by: @hughfAvoid midea…. It will come from freedom and be fitted with a LLH or PHX that will cripple the efficiency.
That's a shame. I was beginning to veer towards Midea. What's the issue with freedom/LLH/PHX? I obviously need to do some more research, but could you provide a quick summary?
Thanks
LLH - low loss header, basically some kind of buffer tank, I don't know the details.
PHX = plate heat exchanged, which in your water tank or buffer will lose you energy compared to better heat exchangers.
Both of these are just a way to provide hydraulic separation between the heat generator and the emitter circuit. It wouldn't matter if we weren't living in a country with the largest ratio between electric and gas costs. That means we're chasing every ounce of efficiency.
Heat pumps are always advertised against direct electric heating (in foreign lands, where most of them are manufactured), and in that case they are always cheaper to run. When comparing against gas, you need to chase every ounce of efficiency, and that means avoiding hydraulic separation.
Hydraulic separation makes it very easy to install without there being any risk of low flow errors causing an issue. Heat pumps delivers heat at whatever flow it wants into the buffer/LLH/PHX, and the heating circuit can pump from the other side of this separation at whatever flow rate the radiators/pipework limit you to.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
On the topic of low loss headers and PHX, I did a search online and found this blog post thing by a Grant person,
https://www.grantuk.com/about/blog/the-case-for-the-low-loss-header/
Having a scan through, it seems to me that their opinion makes sense if you don't bother designing and building the system carefully and just whack it in instead of a boiler...
Posted by: @guthrieOn the topic of low loss headers and PHX, I did a search online and found this blog post thing by a Grant person,
https://www.grantuk.com/about/blog/the-case-for-the-low-loss-header/
Having a scan through, it seems to me that their opinion makes sense if you don't bother designing and building the system carefully and just whack it in instead of a boiler...
As I said (or at least I think I said, perhaps I said it on buildhub), it only matters as we are chasing efficiency numbers because we need to compete with gas. In countries where the alternative is direct electric heating, if your heat pump runs at a cop of 2.5, it matter a lot less.
When we see the levies moved off electric and added onto gas, then it won't matter and we can easily install more heat pumps without needing system redesign/rework.
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
The major drawback with that philosophy, is there will then be the need for more electrical energy generation and transmission, which in turn will increase the amount of electricity supply infrastructure improvements that will be require. Guess who will have to pay for all those improvements?
If everyone concentrates upon reducing energy consumption, then that will help reduce the costs for everyone.
@derek-m Indeed.... insulate britain had the right idea, but just went about getting the message across in the worst way possible...
Off grid on the isle of purbeck
2.4kW solar, 15kWh Seplos Mason, Outback power systems 3kW inverter/charger, solid fuel heating with air/air for shoulder months, 10 acres of heathland/woods.
My wife’s house: 1946 3 bed end of terrace in Somerset, ASHP with rads + UFH, triple glazed, retrofit IWI in troublesome rooms, small rear extension.
Returning to the LLH/PHX question, would it be fair to say that these things essentially trade performance (efficiency) for robustness?
I guess if a large number of end-users just want a set-and-forget system, or don't have the capacity to monitor and fine-tune themselves, then this might be a reasonable approach, depending on the relative cost/benefits.
EPC inspection happened this morning (£60, 30 mins). Waiting with baited breath for results.
Posted by: @mattcReturning to the LLH/PHX question, would it be fair to say that these things essentially trade performance (efficiency) for robustness?
I guess if a large number of end-users just want a set-and-forget system, or don't have the capacity to monitor and fine-tune themselves, then this might be a reasonable approach, depending on the relative cost/benefits.
EPC inspection happened this morning (£60, 30 mins). Waiting with baited breath for results.
Buffer tanks, LLH's and PHE's were required in systems using gas or oil boilers, where radiators would be fitted with TRV's, or in zoned systems where zone valves could be opening and closing.
When any of the above items are used within an ASHP heating system, they not only make the system operation more difficult to balance, but also can dramatically reduce overall operating efficiency. They should therefore be avoided if at all possible.
It is the responsibility of the installer to provide the customer with a correctly operating heating system, that is not using more electrical energy than is reasonably required. Allowing installers to include any of the above items, merely allows the installer to provide a system that works, but removes the necessity for the installer to have to correctly optimise the system operation.
It is like selling a person a car, but insisting that they drive everywhere with the engine revving above 5000rpm. It gets the car user from A to B, but I suspect the fuel economy will be far from ideal.
EPC results are in. We got a 73 (C) with recommendations for additional floor insulation and solar. Nothing on wall or loft insulation, so it looks like we're good to go.
Returning to the question of the Mixergy cylinder, I found this article helpful.
https://energy-stats.uk/mixergy-heat-pump-performance/
I had previously been told that I would need to get the 'heat pump kit' with the Mixergy cylinder, which appears to be a PHX. According to the article, this is needed because the coil in the indirect version of the Mixergy is too small for use with a heat pump. Given this information (and this forum's aversion to PHX's) I'm probably going to drop the Mixergy idea and go with a conventional indirect cylinder.
Any other comments?
- 26 Forums
- 2,117 Topics
- 46.5 K Posts
- 43 Online
- 4,521 Members
Join Us!
Latest Posts
-
Not sure that's what you meant albeit that the industry...
By JamesPa , 34 minutes ago
-
RE: Replacing Refrigerant on Mitsubishi Heat Pump
So the manual is correct and looks fine to me, to abbre...
By ASHP-BOBBA , 1 hour ago
-
RE: Heat Pump Books For Beginners – Bodge Buster & From Zero To Heat Pump Hero
Hi I, like others, avoid Amazon for ethical reasons....
By Topher , 2 hours ago
-
RE: Benefits of an extra horizontal loop for GSHP
I would deffo install an additional slinky run, especia...
By Transparent , 2 hours ago
-
RE: Say hello and introduce yourself
@editor fab - thanks Mars, and keep up the great work o...
By normpang , 3 hours ago
-
RE: Compressor and Evaporator Stratification
@trebor12345 So I think the 1st zigzag section shows so...
By ASHP-BOBBA , 18 hours ago
-
RE: Is this just haze or something more?
@majordennisbloodnok I was giving a talk to primary sch...
By Toodles , 22 hours ago
-
RE: Tesla Powerwall – More of a ‘Luxury’ Than an ROI Winner!
We had our Tesla Powerwall 3 (and Gateway) installed ea...
By Old_Scientist , 23 hours ago
-
Indeed. With a battery its presumably the battery con...
By JamesPa , 1 day ago
-
RE: No-code, plug-and-play monitoring for your heat pump
To update an ESP device using ESPHome in Home Assistant...
By Grantmethestrength , 2 days ago
-
RE: The good, the bad and the not that great – my heat pump installation
Said I would pop back with a update. Only Mr Jesus h...
By Burtis , 5 days ago
-
RE: Buffers, hot water and cooling
Thats presumably heat pump DT, what about radiator DT a...
By JamesPa , 5 days ago
-
RE: Who's your electricity provider and what's your tariff?
@chandykris Exactly the same here. We now have 13.5kWh ...
By Old_Scientist , 5 days ago
-
RE: Wood burner with ASHP - direct air?
This depends on the size of your wood burner and size/t...
By Lucia , 6 days ago
-
RE: Difficult positioning of air source heat pump
@rikiarn It's a not a buffer it's a volumiser which is ...
By Lucia , 6 days ago
-
RE: Is your heat pump insured?
To make things clear, lots of insurance companies cover...
By Lucia , 6 days ago
-
RE: Boxt Heat Pump Installation Experience
@adrian any updates since installation? How is it perfo...
By Ashfp , 6 days ago
-
@seatonian got your email. Will connect you with a reco...
By Mars , 1 week ago
-
@downfield and @toddles, this isn’t in the settings cur...
By Mars , 1 week ago
-
RE: Homely launched for Grant Aerona ASHP control
I haven't bought the Aerona Smart Controller (£700!) bu...
By Prunus , 1 week ago