Air Source Heat Pumps

zeupater

nande2000 wrote: »

The property was rated at having a Heat loss of 8kw at -5 degc and the previous oil boiler it replaced was averaging 1100 litres of oil over the Oct - March period. In the really cold winter of 2009 we used 2000 litres in the same period. If we assume that 1100 litres is accurate that equates to 11000 kWh/6 months =1833 kWh/month. The heat pump is using 871 kWh over 45 days (831 was a typo sorry). Which is 600 kWh/month. As a very rough estimate of cop I make it 3.055.

Hi

Is the log burner a constant ? ... ie, if it isn't new are you burning the same amount of wood as before the ASHP was installed ?

Z

nande2000

zeupater wrote: »

Hi

Is the log burner a constant ? ... ie, if it isn't new are you burning the same amount of wood as before the ASHP was installed ?

Z

I'd say so. We'd always preferred to have the log burner on instead of oil if we could get away with it. Our house has lots of large south facing windows as well. So on sunny days we get lots of solar gain.

[Deleted User]

andrewlato wrote: »

Hi again,
With reference to my previous thread i have more data on how HP performed.
I've collected some data after fitting sub-meter on HP circuit(no immersion heater connected). We had some various temps so it's good for us see how S1200 coped(or not coped).
I have 7 rads fitted with a total output of 10175W(at delta50deg-manufacturers data). They are oversized by around 20%(calculated heat requirement for gas/oil boiler was around 8.5KW).The total volume of water in the system is 155ltrs (rads,pipes and buffer).
I have disconnected immersion heater so my data is purely for HP and circulation pump(CP). The CP is using 72W in 3rd gear. The HP+CP power input comes to 2.9KW regardless of temp(tested at range from 1deg-8deg) and is significantly more than Trianco claims in their manual. Being non-inverter type i just dont understand why (according to Trianco manual) the power input varies between 2.35-3.05 kw)? But anyway-back to numbers:
I have insulated all the external pipes now so heat loss is minimal.

1. I set temp on the programmer at 50deg with 7deg outside and it took around 1h to recover temp in buffer from 33 to 50deg. It looks like HP is able to produce 10kw at 7deg. Temp in the house around 21deg. It works for about 1h and cools down for 2h.

2. I set temp at 50deg with 1deg outside and pump will work all the time because it cannot reach 50deg.It is still using around 3kw per h but cannot produce 10kw that radiators are able to emit. I lowered temp to 47 and it was also struggling to reaching it.This is the point where pump is going all the time and your bills are getting out of hand.

3. I set temp at 45deg with 1deg outside and it would get there but house gets only about 19deg.The time it took for water temp to recover from 23deg to 45deg is 1h 20min. It cools down after about 1h50min and HP comes on again.It uses 4kwh

4. I set temp at 47deg with 2 deg outside, i get 20deg in the house, it takes 1h25mins to recover buffer temp from 27to 47deg. It gets quite quickly to 43 deg then it struggles a bit but gets there in the end. Uses 4.2kwh in process.

I've worked out that when temp outside is above 3deg and you set water temp at or below 50deg the HP will use an acceptable 29kwh per 24h costing me below 3pounds(on E7) a day for heating alone. One 24h period it's gone up to 48.7kwh!!!(due to low ambient temp at night and too high water temp set on programmer) The issue here is HP not being able to produce required heat output at low ambient temp and by trying to achieve required temp will stay on all the time until user changes settings or temp outside improves. This is very costly!!!
From the heating performance graph (Trianco manual) you can work out that s1200 is not a true 12kw HP(by European Norm). It should be tested and COP measured at -7/35 ,2/35 deg, and 7/35 deg like main brands are. HP apparently has 12kw at 20deg- that is useless info if you using HP for heating only-you are not gonna use it for heating when temp outside is 20deg. Trianco claims to be 'World leading heating engineers" - why wouldnt they test their product to EN like all the others?

Im yet to see it working at below 0deg temp.Im interested about defrost mode-how much the performance will drop -lets say -at -5. I have not yet connected immersion heater( will be connected through E7- to protect myself from huge bills). I just dont want HP to get 'lazy' and work off the back up.It will also make it a bit harder to work out what HP is really worth in terms of KW(should it use immersion-that is) . Im thinking of installing Heat Meter on pipes and the true COP will then be known- it's just the cost of it-around 150quid...
Now we are told that cold weather is coming so i should get a chance of testing it further. And i shall let you know about the outcome...
So far my bills between 28/dec and 12/jan that is 15days cost me 62pounds for all electrics that includes occasional heater coming on when newborn has a bath. The prices im paying are 12.6p day, 4.73p night and 23p standing charge.These prices will go up at next top up in line with current Sparks Energy Prepayment tariff.
Above data shows that you really need to monitor your HP in order to understand how it works and set it up according to your needs.
Thanks for reading.
Andre

Your install makes little sense to me...

12kw heat pump connected to just seven rads that are barely oversized! Sounds like part of the issue is too big a pump or not enough rads. I also find it odd that you have it running overnight on E7? Buffer tank or not are all rads conncted up with correctly sized pipework or is it microbore? Before even getting to the point of choosing a suitable enery tarrif it sounds like some fundamentals have not been followed.

Sorry to be blunt...

zeupater

jeepjunkie wrote: »

Your install makes little sense to me...

12kw heat pump connected to just seven rads that are barely oversized! Sounds like part of the issue is too big a pump or not enough rads. I also find it odd that you have it running overnight on E7? Buffer tank or not are all rads conncted up with correctly sized pipework or is it microbore? Before even getting to the point of choosing a suitable enery tarrif it sounds like some fundamentals have not been followed.

Sorry to be blunt...

Hi jeepjunkie

The radiators aren't oversized at all and are not anywhere near sized to match a 12kW heatpump. At a 50C flow temperature there currently seems to be less than 6kW of heat exchange to the air ....

HTH
Z

andrewlato

jeepjunkie wrote: »

Your install makes little sense to me...

12kw heat pump connected to just seven rads that are barely oversized! Sounds like part of the issue is too big a pump or not enough rads. I also find it odd that you have it running overnight on E7? Buffer tank or not are all rads conncted up with correctly sized pipework or is it microbore? Before even getting to the point of choosing a suitable enery tarrif it sounds like some fundamentals have not been followed.

Sorry to be blunt...

No probs Jeepjunkie,
Dont forget that this HP is only 12kw at 20deg. At the expected average temp of 5deg it can produce 7.6kw. It should never be advertised as 12kw otherwise ie Panasonic Aquarea 7kw(7/35) could be advertised as 10kw.
The reason i was using E7 is because i had storage heaters before (on E7)and wanted to see if it work cheaper to stay on E7 or not. If I use it without timed programmer (24hrs constant on-off) it will use some hours of E7 in process.
22mm from HP to manifold, then 15mm PEX to every rad on separate circuit with CP Wilo 3m3 per h
Today with 0deg outside HP is only getting up to 41deg, i get 17deg in the house.
I changed settings to 20.30-7.30 ON, and 12-15 ON.That gives me 18deg in house , and slightly more during night.Immersion is still disconnected.
The whole exercise I do is to show that installation can be done at much cheaper price than 11k or 14k quoted here. Also it shows that 'World leading heating Engineers' are selling cheap chinese HP that get MCS accredited and sold as Top Brands here. Read S1200 manual and see how much info (compare to main brands) is missing. Manual states 'it is recommended to use 28mm pipe', also buffer size 12x EXPECTED KW. How would you size the buffer then...at 12kwx12 or maybe 7.6kwx12 or maybe at 9kwx12 if you not planning to heat your house with outside temp more than 10deg...
If i put more rads on this HP - do you think it will produce more hot water -I dont think so ,or if i downsize HP will it make my house warmer- i dont think so..
I have paid mere 1300 for HP and I expected it not to perform as claimed in manual-so Im not too worried but if somebody could explain to me the difference in power input(as per manual and actual) and perhaps tell me what could i do to get the HP below 3kwh input Id be grateful a this is the only thing Im dissapointed about.
Im quite happy to listen to all views and learn where i went wrong or how to improve performance of this installation

andrewlato

zeupater wrote: »

Hi jeepjunkie

The radiators aren't oversized at all and are not anywhere near sized to match a 12kW heatpump. At a 50C flow temperature there currently seems to be less than 6kW of heat exchange to the air ....

HTH

If rads were bigger(more water in the system) in my opinion water wouldnt get heated to even 41deg at present temp outside of 0deg or Am I wrong.
I oversized HP on purpose so it could compensate for what it cant do ie provide heating performance as per s1200 manual.

zeupater

andrewlato wrote: »

If rads were bigger(more water in the system) in my opinion water wouldnt get heated to even 41deg at present temp outside of 0deg or Am I wrong.
I oversized HP on purpose so it could compensate for what it cant do ie provide heating performance as per s1200 manual.

Hi

The way I see it is that the more volume water you have, the only difference is the time it will take to reach temperature, or cool .... heat transfer to air is related to the surface area of the radiators, not the mass of water .... quite simply, if your heat source adds more heat than the radiators can transfer, the system will continue to become warmer until the thermostatic setting is reached, or the efficiency of the heatsource can provide no more heat.

The idea of a dedicated inline cylinder in a HP system is to provide a 'heatbank' specifically to increase the volume/mass of fluid in order to provide a 'warm-start' when the system cuts in. I would expect that such a setup would only be needed where there is no direct transfer to alternative thermal mass through U/F slab heating. or multiple heat sources are being used (log burner etc.), but a HP heating engineer would need to confirm this.

Running radiators at 41C in a house at 21C would suggest that radiators would need to be sized at 2.5x (50/20) their nominal T50 rated output, however, the radiators will not be transferring heat even at this rate until the system has reached 41C. The rate of increase of system temperature can be roughly estimated by rule of thumb .... 1kW heats 1 tonne by 1C in 1 hour.

I'd rather have the radiators considerably oversized which would result in a lower running temperature and therefore a higher COP expectation .... but then again, we don't have a HP and all above is based on simple logic and my recollection of experiences of a number of people I know who do have such units, although mainly ground source ....

HTH
Z

[Deleted User]

andrewlato wrote: »

No probs Jeepjunkie,
Dont forget that this HP is only 12kw at 20deg. At the expected average temp of 5deg it can produce 7.6kw. It should never be advertised as 12kw otherwise ie Panasonic Aquarea 7kw(7/35) could be advertised as 10kw.
The reason i was using E7 is because i had storage heaters before (on E7)and wanted to see if it work cheaper to stay on E7 or not. If I use it without timed programmer (24hrs constant on-off) it will use some hours of E7 in process.
22mm from HP to manifold, then 15mm PEX to every rad on separate circuit with CP Wilo 3m3 per h
Today with 0deg outside HP is only getting up to 41deg, i get 17deg in the house.
I changed settings to 20.30-7.30 ON, and 12-15 ON.That gives me 18deg in house , and slightly more during night.Immersion is still disconnected.
The whole exercise I do is to show that installation can be done at much cheaper price than 11k or 14k quoted here. Also it shows that 'World leading heating Engineers' are selling cheap chinese HP that get MCS accredited and sold as Top Brands here. Read S1200 manual and see how much info (compare to main brands) is missing. Manual states 'it is recommended to use 28mm pipe', also buffer size 12x EXPECTED KW. How would you size the buffer then...at 12kwx12 or maybe 7.6kwx12 or maybe at 9kwx12 if you not planning to heat your house with outside temp more than 10deg...
If i put more rads on this HP - do you think it will produce more hot water -I dont think so ,or if i downsize HP will it make my house warmer- i dont think so..
I have paid mere 1300 for HP and I expected it not to perform as claimed in manual-so Im not too worried but if somebody could explain to me the difference in power input(as per manual and actual) and perhaps tell me what could i do to get the HP below 3kwh input Id be grateful a this is the only thing Im dissapointed about.
Im quite happy to listen to all views and learn where i went wrong or how to improve performance of this installation

Hi,

It sounds like you are running a low temp ASHP as if it were a GCH system. I don't know your house but rule of thumb for ASHP rads will be something like 2-3 times the size of rads sized for a gch system. Hence why you get triples now.

By design ASHPs like to run for long periods at the lowest temp you can get away with for max cop.

I could be wrong but it sounds like yours is doing a lot of cycling which will reduce compressor life and cause the issues you are experiencing.

As a comparison our ASHP which is not much bigger runs 13 fan coils, 1 large towel rail and UFH. The fan coils suck so much heat out the pipes the one going in is hot the one going out is barely warm so high flow rates are essential.

All the best!

PS A 14kw Ecodan without tank/controls is £4200ish

Bonny2000

Just wondering if anyone could assist me. We recently moved into a house which has an eco dan heat pump. Can anyone tell me what setting people have their control panel set to. My house seems too hot or cold. Do people also use seperate room thermostats to control the room temperatures. I was also wondering if people kept their heating on constantly or on a timer? Thanks in advance.

albyota

Bonny2000 wrote: »

Just wondering if anyone could assist me. We recently moved into a house which has an eco dan heat pump. Can anyone tell me what setting people have their control panel set to. My house seems too hot or cold. Do people also use seperate room thermostats to control the room temperatures. I was also wondering if people kept their heating on constantly or on a timer? Thanks in advance.

Hi, ideally, it should be timed to come on in the morning and then be controlled via the room stat, the room stat should be programmable so you can adjust the temperature at different times of the day to suit your lifestyle, Heat pumps cannot do heating at the same time as doing the domestic hot water cylinder, so it is best to program the domestic hot water to come on early in the morning, or last thing at night so the rest of the time the Ecodan is just doing the heating.
The Ecodan also has weather compensation so it will adjust the heating water temperature depending on the outside temperature, yours may need adjusting to avoid the unit cycling.