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Author Topic: "Best" Radiators for use with Heat Pump  (Read 1972 times)
Bikerzz
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« on: February 09, 2018, 03:51:14 PM »

Is it as simple as looking for the highest BTU that fits?
Presumably I look at aluminum ones only?
Any recommendations best place to get these?
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linesrg
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« Reply #1 on: February 09, 2018, 08:07:09 PM »

Bikerzz,

Surely you need to start with determining how much energy is needed to heat each space then work out your radiator sizings based on the likes of a delta of 25degrees C?

As I've mentioned elsewhere I used Stelrad K3 which are simple double banked pressed steel radiators with another layer.

Depending on how much energy you require per space there are options like the Dimplex SmartRad's or Myson ULow's?

Regards

Richard

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16 x BP380 on a Lorentz tracker/ SMA SB2500, 16 x Chinese 80W/ SMA SB1700, 16 x BP380/ SMA SB1700. CTC GSi12 heat pump/ Gledhill ASL0085 300litre EHS/ 3off Navitron 4720AL solar ET panels and an Immersun T1060/ T1070/ T1090. 7 x Tianwei 235W/ Aurora PVI 3.6kW/ Growatt SP2000 c/w 5kWhr battery.
rogeriko
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« Reply #2 on: February 09, 2018, 08:22:26 PM »

For a heat pump the best radiators will have fans to get the low temperature heat out. Convection dosn't work at 35 degrees.

https://www.plumbnation.co.uk/site/smith-s-ecovector-ll1200-low-level-hydronic-fan-convector/?gclid=CjwKCAiAqvXTBRBuEiwAE54dcJ7Pqa3kzKoaI5faDExas9yozqjYcN23k_iNI2RX3ULFVO3BqkGXJhoCJxUQAvD_BwE

http://esheatpumps.com/products/fc-fan-coils/
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martin W
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« Reply #3 on: February 12, 2018, 08:25:19 AM »


Is there any info about this anywhere, test's etc? I run my stelrads at 50 deg C flow temperature, and they give out heat wonderfully...

What would be the cut off temperature, below which the radiators won't convect..
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Philip R
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« Reply #4 on: February 12, 2018, 08:51:04 AM »

Do as Richard says, Convection  works at any delta t. You just need to go large, use the heat output calculator.
Aluminium radiators do not offer any more heat output than a well finned steel panel rad. K2 or K3 will convect he's at lower temperatures. Ally one are lightweight and easy to lift.
If you go for fan convectors, you will have to defluff them, especially if you have carpets and pets.
The fan noise is perceptible. The bearings wear out, then you will either have fun and great expense getting the fans replaced.

I fitted column radiators to replace steel panels in a groud source heat pump heated property, a manor house,
the rads work well, perceptibly warm but heat the building effectively.

Philip R
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A.L.
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« Reply #5 on: February 12, 2018, 04:05:04 PM »

hello,

- for simple 'panel' radiators if the room has a temperature of 20C the figures below give the relative output compared to a radiator with a entry temperature temperature of 80C

0.798@70C, 0.605@60C, 0.423@50C, 0.256@40C, 0.108@30C
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rogeriko
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« Reply #6 on: February 12, 2018, 10:01:44 PM »


Is there any info about this anywhere, test's etc? I run my stelrads at 50 deg C flow temperature, and they give out heat wonderfully...

What would be the cut off temperature, below which the radiators won't convect..


hello,

- for simple 'panel' radiators if the room has a temperature of 20C the figures below give the relative output compared to a radiator with a entry temperature temperature of 80C

0.798@70C, 0.605@60C, 0.423@50C, 0.256@40C, 0.108@30C


Thats what I said at 30 degrees centigrade a 3kw radiator gives out only 300 watts or 1 tenth of the design ratings.
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linesrg
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« Reply #7 on: February 13, 2018, 04:20:58 AM »

Good Morning All (from Doha airport),

My assortment of K2 and K3 Stelrads have worked well enough so far since we installed our heat pump.

The temperature going out from the heat pump has been in the range 35 - 42 degrees C. There is still work to be done on improving the house with the Hall, Living Room and downstairs bathroom to be ripped out with the attendant radiators being replaced with UFH.

When I get back I have to complete removing the old cold water header tank from the attic and putting another 100mm layer of fibreglass in that part of the roof.

Step by step.........

Regards

Richard
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16 x BP380 on a Lorentz tracker/ SMA SB2500, 16 x Chinese 80W/ SMA SB1700, 16 x BP380/ SMA SB1700. CTC GSi12 heat pump/ Gledhill ASL0085 300litre EHS/ 3off Navitron 4720AL solar ET panels and an Immersun T1060/ T1070/ T1090. 7 x Tianwei 235W/ Aurora PVI 3.6kW/ Growatt SP2000 c/w 5kWhr battery.
DonL
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« Reply #8 on: February 13, 2018, 01:43:08 PM »

I too used conventional panel radiators with size adjusted according to the de-rating factors already given. It's surprising how much more surface you can get into the same area by specifying  doubling up or tripling panels, adding more fins etc. Panel radiators without moving parts are simple, extremely quiet, and inexpensive. I've been fully satisfied using them with my ASHP.
Obviously you have to size them properly for the design temperature using the de-rating factors.
Don
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Bikerzz
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« Reply #9 on: March 03, 2018, 06:22:26 PM »

Cheers for this. So take my worse room, playroom north facing and 2 outside walls north facing with 8m2 of windows (will be triple glazed), pitched roof with 100mm insulation but will go 400mm soon.

2.3m Height
1.85m Wide
6.5m Long

So its 4570 - 5770 BTU depending on the calculator you use...... Add in a 40c heatpump factor and you need a rad with 18,000BTU.....
Really? I have a max space really of 2300mm wide but as high as you like (2300mm ceiling) Which is impossible with only 1 rad it seems. At the moment it has a 1000x600mm single and its cold but thats with probably 70c water from a oil boiler. (Must get temperature gauge from work on Monday)

P.S. Which is best BTU calculator to use? Most options, just most accurate.
« Last Edit: March 03, 2018, 06:49:35 PM by Bikerzz » Logged
A.L.
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« Reply #10 on: March 03, 2018, 08:02:53 PM »

hello again,

So its 4570 - 5770 BTU depending on the calculator you use...... Add in a 40c heatpump factor and you need a rad with 18,000BTU.....
Really? I have a max space really of 2300mm wide but as high as you like (2300mm ceiling) Which is impossible with only 1 rad it seems. At the moment it has a 1000x600mm single and its cold but thats with probably 70c water from a oil boiler. (Must get temperature gauge from work on Monday)

A 2070mm x 720mm double panel double finned will give your required output. A single panel, with fins, 1000mm x 600mm at 70C will have an output around 3500 Btu
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Bikerzz
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« Reply #11 on: March 03, 2018, 09:01:25 PM »

Cheers Al

So using Stelrad here https://www.stelrad.com/products/core-steel-panel-radiators/compact/
700x2200 gives me 14,700 BTU

Just need to find something nicer looking that the Mrs will allow. Where did you see a 2070x720?
« Last Edit: March 03, 2018, 09:06:17 PM by Bikerzz » Logged
linesrg
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« Reply #12 on: March 03, 2018, 09:21:27 PM »

Bikerzz,

I don't know what you are doing to improve the insulation values of the playroom you're heating. Are you able to put any insulation under the floor, are you insulating the walls?

As you identify you're aplyng a multiplication factor of some 0.308 for a deltaT of 20oC so reducing the need for heat input equates to a smaller radiator.

The trade off might be the disruption involved in improving the insulation.

I very much look forward to the day when there is no more woodworm riddled lath and lime plaster to remove.  Smiley

Regards

Richard
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16 x BP380 on a Lorentz tracker/ SMA SB2500, 16 x Chinese 80W/ SMA SB1700, 16 x BP380/ SMA SB1700. CTC GSi12 heat pump/ Gledhill ASL0085 300litre EHS/ 3off Navitron 4720AL solar ET panels and an Immersun T1060/ T1070/ T1090. 7 x Tianwei 235W/ Aurora PVI 3.6kW/ Growatt SP2000 c/w 5kWhr battery.
Bikerzz
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« Reply #13 on: March 03, 2018, 10:13:40 PM »

Hi Richard

I have a block and beam floor with a screed, which today I have dug into to see how deep before I hit concrete. I have about 85mm to play with so Im thinking 50mm insulation,then 18mm board, then 10mm ish for the laminate floor.

The room at the moment has a 650x800mm single old rad (1994) but with the oil boiler on gets the room to approx 17c (Again I dont know water temp from oil boiler), but I want to go to an air source pump in the future, hence big rads wanted.

Do you have a good BTU calculator that can take these sorts of things into account. One I have are generic double glassed windows and cavity walls.
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linesrg
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« Reply #14 on: March 04, 2018, 08:34:41 AM »

Bikerzz,

I have an old Windows based programme I use (can't recall the name off the top of my head). The beauty of it is that although it doesn't give every possible combination of construction window and door types it does allow you to alter the 'U' values.

Thus I can go to such as the Celotex site input the wall/ floor combinations to derive a 'U' value then enter that into the programme. I would say that it produces pretty good results based on what I see has been required in the past in terms of heating input.

I'm currently at the flat in Aberdeen and due back home tonight or tomorrow morning. I'll flash up the old windows laptop and get a copy. If you send me you EM address by PM I'll forward a copy to you.

Regards

Richard
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16 x BP380 on a Lorentz tracker/ SMA SB2500, 16 x Chinese 80W/ SMA SB1700, 16 x BP380/ SMA SB1700. CTC GSi12 heat pump/ Gledhill ASL0085 300litre EHS/ 3off Navitron 4720AL solar ET panels and an Immersun T1060/ T1070/ T1090. 7 x Tianwei 235W/ Aurora PVI 3.6kW/ Growatt SP2000 c/w 5kWhr battery.
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