ASHP or GSHP or Solar panel

albyota

paceinternet wrote: »

Is the above reference about an Ecodan which could have been running on the circa 4 minute defrost cycle?
If so, there have been other posts elsewhere about incomplete defrosting in certain weather conditions. Is it adjustable on the Ecodan, or something you live with?

yes, pace, it is the Ecodan, the defrost cycles are not adjustable, the Ecodan has multiple sensors on the refrigerant gas side and also on the water side within the plate HEX, the unit uses very complicated software algorithms, quite intelegent, using reverse flow 4 way valve.
The reason for short and / or incomplete defrosts at high humid, low ambient, between say minus 5 and plus 2, are due to low flow rates / low temp through the HEX, also if the controls i.e. programmer, room stat, cause the unit to switch off for long periods, i.e. room at required temperature, roomstat satisfied, then the plate HEX will cool down, when the room temp drops and calls for heat again, the unit has a delay getting the HEX back up to temp, the outdoor unit will then work at its maximum to achieve this (inefficient, costly), If the flow rates are too low, then there is no energy in the heating circuit and the heat exchanger drops to near zero and will go into defrost to protect itself, from then, the unit is always trying to recover, to avoid this, the room stat is better positioned in one of the cooler rooms, all radiators fitted with TRV's to look after each room, and use digital programmable thermostats, and leave the system on ECO, the ECO setting uses the weather compensation sensor and adjust the water flow temperature according to the outdoor temp, e.g. if its minus 10, the water temp would be hotter 50/55, whereas, if it is plus 7, the water would be cooler 35/40, so best set on ECO and let it do its thing......try to avoid controlling it like a conventional gas/oil heating system.

Crikey....I went on a bit there......;)

lovesgshp

albyota wrote: »

yes, pace, it is the Ecodan, the defrost cycles are not adjustable, the Ecodan has multiple sensors on the refrigerant gas side and also on the water side within the plate HEX, the unit uses very complicated software algorithms, quite intelegent, using reverse flow 4 way valve.
The reason for short and / or incomplete defrosts at high humid, low ambient, between say minus 5 and plus 2, are due to low flow rates / low temp through the HEX, also if the controls i.e. programmer, room stat, cause the unit to switch off for long periods, i.e. room at required temperature, roomstat satisfied, then the plate HEX will cool down, when the room temp drops and calls for heat again, the unit has a delay getting the HEX back up to temp, the outdoor unit will then work at its maximum to achieve this (inefficient, costly), If the flow rates are too low, then there is no energy in the heating circuit and the heat exchanger drops to near zero and will go into defrost to protect itself, from then, the unit is always trying to recover, to avoid this, the room stat is better positioned in one of the cooler rooms, all radiators fitted with TRV's to look after each room, and use digital programmable thermostats, and leave the system on ECO, the ECO setting uses the weather compensation sensor and adjust the water flow temperature according to the outdoor temp, e.g. if its minus 10, the water temp would be hotter 50/55, whereas, if it is plus 7, the water would be cooler 35/40, so best set on ECO and let it do its thing......try to avoid controlling it like a conventional gas/oil heating system.

Crikey....I went on a bit there......;)

Looking at the Ecodan manual, it seems that you do not have a full range of parameters for control, just the ECO setting for defrost via outside temp sensor.
Another point, if you are using TRV valves on a rad system, do they all have bypass valves, as this could affect performance levels. Recommendation is that TRV's are fully open without them.
In addition, a room sensor is basically meant to be used if you have a secondary system, e.g woodburner etc., so you can override the ext sensor, but it is better where the 2 can " talk together ". The Eco setting gives some override, so a good point if you cannot adjust manually.

albyota

Geotherm wrote: »

Looking at the Ecodan manual, it seems that you do not have a full range of parameters for control, just the ECO setting for defrost via outside temp sensor.
Another point, if you are using TRV valves on a rad system, do they all have bypass valves, as this could affect performance levels. Recommendation is that TRV's are fully open without them.
In addition, a room sensor is basically meant to be used if you have a secondary system, e.g woodburner etc., so you can override the ext sensor, but it is better where the 2 can " talk together ". The Eco setting gives some override, so a good point if you cannot adjust manually.

Mmmm, after owning one for two and a half years, and specifying over 90 installations, I think I have a fair idea of how they work and how to set-up and operate them, what parameters they have and what controls are required and diagnostics and fault codes etc.

I have UFH myself, but as for installations with radiators and TRV's, any heating system works better and more efficiently with TRV's, especially a heat pump, only one radiator is required without a TRV which is used as the bypass.

Here in the UK, we use standard digital programmable room thermostats (Danfoss), so different temperatures can be set at different times of the day/night.

The ECO setting is nothing to do with the defrost! The ECO/BOOST 2 way switch, in BOOST provides water at constant temp, (settable between 30 and 55) the ECO (Weather compensation) is adjustable and very straight forward,
for example, a heat curve with 55C water at minus 5 or below, and 25C at plus c12/15, off at 17C, fully adjustable.

For fear of proving Cardew and others 'Right' I really do think ASHP and GSHP are a world apart....IMO.......far too many parameters/settings, spells disaster for the commissioning engineer and the end user,
kiss (Keep it simple stupid). :eek:

Pincher

They need to take a leaf out of computer architecture, dual channel, aka interleaving. Alfa Romeo owners can tell you you need to buy two, so you can drive one while the other is being repaired.

I propose a configuration where you have a combined solar thermal panel with the radiator under-mounted: you put two of these on the roof. They need a powered fan and sensors, so you need at least refrigerant flow and return hoses, power and data cables.
Each panel can act as either heat source or heat sink.

The heat pump can be located in the loft, in a vibration harness, but ideally they should design it with balancer shafts or something to minimise vibration.

So we use panel B whilst panel A is defrosting, possibly using the heat generated using B!

Alternatively,

http://www.atmos.co.uk/default.asp?contentID=588

The Atmos Combinair extracts heat from the stale air going out of the house. Even after heat recovery, there must be heat left in the exiting air. Let us say the outside temperature is -10 degrees, and the indoor temperature is +20 degrees. So, we use a MVHR to bring in fresh air, so the stale indoor air gives up its heat in the heat exchanger and becomes 5 degrees. Wouldn't it be great if we could further extract heat using the heat pump so the stale air leaving the house is at -5 degrees!

So, we could have one combi-solar panel (A), and one stale air radiator (B), and alternate between these two while the other is defrosting.

Using a single cage with one heat pump and one radiator is so monogamous.

albyota

yeah, but now with the wireless, bluetooth refrigerant gas in plastic carton, buy two get one freeon, put the solar thermal pipe exchanger under the solar PV to aid cooling, better efficiencies, gain some heat, duct that to the fan coil to increase the COP, put the phone in the fridge, let the dog out..........where was I?

I'm too tired for this.......

Pincher

Now that you've brought the fridge into it......

http://www.norcool.com/

Disconnect the compressor from the prefabricated cold room, plumb it into the loft heat pump, and there you are.

Obviously somebody has to design the multiway refrigerant router and the computer to manage it all.

They probably did the work for the Mir spacestation already.:)

lovesgshp

albyota wrote: »

Mmmm, after owning one for two and a half years, and specifying over 90 installations, I think I have a fair idea of how they work and how to set-up and operate them, what parameters they have and what controls are required and diagnostics and fault codes etc.

I have UFH myself, but as for installations with radiators and TRV's, any heating system works better and more efficiently with TRV's, especially a heat pump, only one radiator is required without a TRV which is used as the bypass.

Here in the UK, we use standard digital programmable room thermostats (Danfoss), so different temperatures can be set at different times of the day/night.

The ECO setting is nothing to do with the defrost! The ECO/BOOST 2 way switch, in BOOST provides water at constant temp, (settable between 30 and 55) the ECO (Weather compensation) is adjustable and very straight forward,
for example, a heat curve with 55C water at minus 5 or below, and 25C at plus c12/15, off at 17C, fully adjustable.

For fear of proving Cardew and others 'Right' I really do think ASHP and GSHP are a world apart....IMO.......far too many parameters/settings, spells disaster for the commissioning engineer and the end user,
kiss (Keep it simple stupid). :eek:

I bow to your superior knowledge Albyota. The Ecodan is only a UK model, so perhaps the idea is to "kiss".
I compared the Ecodan instructions to the IVT Optima, which obviously is a much longer established ASHP unit. At least on that you can change defrost settings (via the installer menu ). They also suggest all TRV valves are fully open.
The comment I made was based on that information and nothing to do with a GSHP.

st999

So nobody saved any money then?

lovesgshp

st999 wrote: »

So nobody saved any money then?

Couldn't give you an answer to that on my system. I use circa 10,000KWH of electricity per year for the whole house, plus circa £100 lpg for hob cooking.
House 120 sq mtrs, 250 years old with 60 cm stone walls, underfloor heating, low insulation with a 11KW GSHP. Altitude 400 mtrs.

Probably you could work the cost out to UK electricity prices.

TiredGeek

Geotherm wrote: »

Couldn't give you an answer to that on my system. I use circa 10,000KWH of electricity per year for the whole house, plus circa £100 lpg for hob cooking.
House 120 sq mtrs, 250 years old with 60 cm stone walls, underfloor heating, low insulation with a 11KW GSHP. Altitude 400 mtrs.

Probably you could work the cost out to UK electricity prices.

But you are in Italy, with respect, we don't grow olives and lemons in the Uk for a reason - it's too bloody cold!
You might have winters as cold as we do but your summer is substantialy warmer which both reduces the number of months you need heating and it warms the fabric of the building so you need a bit less from that also.

You use about £1000 a year for everything, mine use about £10 a day just for the ASHP, so I'll use that much in just 100 days the way they're working (or not) at present. I would guess you get good weather from mid March to early November, in northern Scotland I get it from late April to early September, so I have more winter to deal with (if you can call northern Scotlands weather "good" at any time)

Maybe the answer isn't ditching the ASHP for something else, it's getting out of this screwed up country and retiring somewhere warm