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Author Topic: New ASHP Install  (Read 10741 times)
dullnote
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« Reply #15 on: December 06, 2011, 03:06:22 PM »

Hi Stationhouse and Bassman I would be grateful if you could keep us up to date with the ASHP over the winter. I am looking into these I have 4 bed detached house two years old, full underfloor heating running a LPG boiler. Last year at this time casting me approx £10 a day to run, I have fitted a woodburning stove this year and now have the gas bill down to £5 to £6 per day. (at present time due to cold weather) last year worst was £12 a day but it was never above -5 degrees.

I would like to see the running costs, also info on any noise issues

Thanks

Dullnote
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StationHouse
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« Reply #16 on: December 06, 2011, 03:24:00 PM »

Can do.

My meter readings are bit adhoc as I do it as and when I get a min but at least once a week. From that I try to calculate averages over the year as with any heating sytem. The thing to bear in mind are my readings are for whole house usage not just the ASHP.

I don't think I've built a big enough balance with nPower for winter useage but hoping the lighter nights next year will pull things back with the PV.

On my tariff over the last four months I'm using about £65 a month for everything.

As we are all on different tariffs I'll just give you the units used with a note of our useage patterns etc.

Cheers.
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mpooley
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« Reply #17 on: December 06, 2011, 05:28:48 PM »

I am very interested in hearing you opinion on your fan convectors as I am in a situation where i cant have underfloor heating installed.
which ones did you use?



thanks

Mike

 
« Last Edit: December 06, 2011, 05:52:14 PM by mpooley » Logged

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StationHouse
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« Reply #18 on: December 07, 2011, 08:13:30 AM »

I am very interested in hearing you opinion on your fan convectors as I am in a situation where i cant have underfloor heating installed.
which ones did you use?



thanks

Mike

 

Hi,  we went for the white glass fronted Dimplex SmartRads. Size them at the lowest fan speed to the room so they run at their quietest. We went for them to keep the cop/efficiency as good as it could be as they run at pretty much UFH temps. An oversized rad system needs a much higher heat curve plus the rads need to be huge. SmartRads are similar size to GCH rads. One thing to note is they need their own electrical circuit but as we were decorating it was no big deal. They are not cheap as we needed 13 but was hugely cheaper than retro fitting UFH. In saying that we put wet ufh in the bathroom as it was a small space. The beauty of fan convectors is unlike normal rads they hold very little water, about 1lt, so you get very fast warm up/response times and less work for the ASHP to do. Although we have a stat for the UFH in the bathroom and a wireless stat for the fan convectors when the house is pretty much at temp its cool air they are blowing which seems mad that the house is sitting 20c as a result. You only ever feel them blow warm air if the system is say changing from 17c to 20c in the morning then it settles back to blowing cool air. Conversely if the system goes from 20c to 17c at night the fan convectors all automatically turn off as they no longer sense warm water flowing to them... Warranty support has been great as we had a couple of noisy ones.

Cheers
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mpooley
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« Reply #19 on: December 07, 2011, 10:10:03 AM »

Thanks!
What does "An oversized rad system needs a much higher heat curve" actually mean ?
sorry but im a bit thick lol

One worry I have would be the fan noise? but more worryingly my wife wont have our under kitchen fan rad on at all, as unless the air is coming out hot she reckons it's just a draught ! so i think she might hate having cool air blown about in the lounge!

Mind you she is bonkers but what can i do lol

mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
StationHouse
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« Reply #20 on: December 07, 2011, 10:19:02 AM »

You only feel the cool air if you are right inches from them otherwise the rooms feel nice and warm with no draft.

Heat curve is simply this.

Very briefly with arbitary figures as i cant remember what mine are. When the outside temp is say for example -10c the ASHP heats water to 40c and when the outside temp is 15c it heats water to 20c. 

Cheers
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mpooley
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« Reply #21 on: December 07, 2011, 04:42:23 PM »

thanks  signofcross
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
JonG
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« Reply #22 on: December 07, 2011, 10:50:53 PM »

Hi Mike whilst fan coils are great for getting flow temps low, a heat pump runs better with big thermal masses. This is why UFH in a screed is so good. It takes time to warm it gently with a low flow temp and then gives it off slowly over time. This means that the HP runs long and low to achieve temperature in the screed and in the shoulder periods it will then be held off for longer whilst the screed acts as a large radiator.

With a reduced system volume there is a potential for cycling because the low volume of water will reach temp quickly and then cycle the heat pump as the temp fluctuates, because just as the system will heat quickly it will also cool quickly where ideally the HP would run for longer to achieve temperature and then the mass in the system would damp out short on off periods.

UFH in screed is great, cast iron rads are OK but we also get reasonably good results with standard oversized panels. K3 units are now available that are triple panel, triple convector, which reduce the overall footprint but stand further off the wall.

A competent installer should heat loss each room and then apply radiator manufacturer factors to the heat loss to calculate the size of radiator based on the flow temp and design internal temp of the room.   

Seriously consider a buffer too, this increases system volume and therefore mass and also introduces a host of other benefits that I have referred to in another post.

Cheers

Jon
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mpooley
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« Reply #23 on: December 07, 2011, 11:14:59 PM »

Thanks Jon - Yes I have noticed your other posts
You seem to know what you are talking about.

I assume you are an installer but I bet you don't live anywhere near me  snow

Mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
bassman
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« Reply #24 on: December 12, 2011, 01:24:03 PM »

Hi

Just added a link to my post

https://picasaweb.google.com/108455921836178416144/October262011?authuser=0&authkey=Gv1sRgCM-0qfuOjc_9ew&feat=directlink

November 2011 power input
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Daikin 16kW Monobloc ASHP - Stovax 8kW multifuel stove
mpooley
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« Reply #25 on: December 12, 2011, 01:39:27 PM »


Looks low compared to my oil consumption costs !
what size approx house is it ? and is it well insulated?

thanks
Mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
bassman
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« Reply #26 on: December 12, 2011, 03:13:47 PM »

185sq m
200mm loft insul
Cavity wall bead filled
UFH all tiled floor

I have 80% of the building on "heat" at present - with oil it was more like 50%
I was using on average 3000l of oil per year for the last 7 years so I will have accurate figures to compare to
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Daikin 16kW Monobloc ASHP - Stovax 8kW multifuel stove
dhaslam
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« Reply #27 on: December 12, 2011, 03:36:09 PM »

Was the same insulation in place  when you were using 3000 litres of oil per annum?
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
bassman
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« Reply #28 on: December 12, 2011, 04:26:08 PM »

Yes, all that has changed is the heat source
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Daikin 16kW Monobloc ASHP - Stovax 8kW multifuel stove
mpooley
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« Reply #29 on: December 12, 2011, 04:44:31 PM »

Yes, all that has changed is the heat source

wow that's a lot of oil for such a reasonably well insulated house.

my loft area is over 300sq meters - 2 story house
with some solid flint walls but mostly brick /cavity/block with insulation and flint/block/cavity/block - again filled.
270mm loft insulation soon to be topped up to 400mm !!
I have averaged about 3200litres but last year was 3600L

but we don't heat all of it as only use 2 of the 5 bedrooms and its got a huge solid flint walled dining room which we don't bother with in the winter.

hope this winter will be a mild one lol

mike
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It's not easy having a good time. Even smiling makes my face ache.

“Science is the belief in the ignorance of experts.” Richard Feynman
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