Quote for ashp - didnt expect that much!

[Dave Jones]

4 minutes ago, JohnMo said:

You don't even do that anymore, push joints or pressed joints.

 

And really you only need those pipes within 1m of the cylinder and outside, anything inside the heated envelope is heating the house, so unless you are cooling below dew point not much need. In fact Heat Geek say don't bother.

 

our plant room was like a furnace until i lagged everything. press fit is ok where you have room for the big machine, our plumber did it old fashioned way.

[mk1_man]

Also you don't want hot water heating contributing to temps in the house during summer.  My view is insulate everything, gives you option then for using cooling function later on also.

 

If I had access to a press fit tool I may have gone that route. Filled up system this very morning and touch wood no leaks as yet, once system gets some heat in i will be happier 🙂 

[ReedRichards]

23 hours ago, JohnMo said:

And really you only need those pipes within 1m of the cylinder

Because?  Why bother insulating those pipes if you're not bothering to insulate any other pipes within the heated fabric of the building?

[JohnMo]

59 minutes ago, ReedRichards said:

Because?  Why bother insulating those pipes if you're not bothering to insulate any other pipes within the heated fabric of the building?

Missed a bit of detail.

 

Cold and hot domestic water 1m from cylinder. All pipes on the heating circuit for the cylinder insulate, so you are not heating the insulated envelope in the summer. Pipes for the central heating circuit, no point insulating. Any void pipes pass through will either will be heated by room above, below or adjacent to by secondary heating from the rooms. As heat always moves to cold. Might not make sense in a high temp heating system, but a heat pump one it should.

[TheMitchells]

I have finally received the heat loss calculations for the 70m2 bungalow.   apparently it is suggesting a 10kW heat pump but the installer is thinking an 8kW would be sufficient.  he's suggested a Samsumg. 

 

I do recall being told that the flow temperature is important for efficiency and lifespan of the heat pump.  I can see a flow temp of 53oC - is this something i should ask about? 

 

Comments gratefully received.  We do need to get this installed soon as my elderly parents feel the cold and are already commenting on the place being cold in the mornings!  (we do have a night storage heater that we can turn on till the new system is installed).

 

heatpump-design-calculations.pdf heatpump-system-performance 7 ellesmere.pdf hotwater-design-calculations.pdf room-by-room-calculations.pdf room-by-room-emitters.pdf

[TheMitchells]

I believe the calculation shows that the bungalow will need 13,350kW to heat the place. But the total electricity used last year for the whole place was less than 12,000kW so is their heat demand calculation incorrect?

 

[Dave Jones]

any flow temp 40c+ is going to painfull to run.

 

is there scope to better the insulation ? 

 

 

[IGP]

If there’s scope to increase the loft insulation to 300mm if not already and fill the cavities with EPS beads then do those first. 

9.5kW for 70m2 seems awfully high. I’d be interested to know how much of that is assumed ventilation losses. 

 

Also yes that’s a high flow temp, very painful. Most of those emitters seem like the minimum they can get away with. I’d be asking them to calculate for 40c flow, and only if the emitters *cannot* be done sensibly, then increase the flow temperature from there. Also, they can get creative having multiple emitters in a room rather than one big one and also going up to 700mm rather than 600mm etc. Lots of ways to skin the cat. 

 

[MikeSharp01]

Not sure where they get, probably missed something I have, the SCOP of 1.75 in HW mode from even the highest temperature output in the heatpump specification is 3.47 @ 55 Deg C after which it drops to 0 which implies it won't go there!

[JohnMo]

Lot of things wrong

 

Heat loss calculation say 5.5kW heat loss. But heat pump at design conditions can put out 9.5kW. it's too big a heat pump.

 

Flow temp is a joke, push for 35 degs, for a decent running cost, otherwise take out a second mortgage. Or just don't bother.

 

 

[sharpener]

29 minutes ago, IGP said:

Also, they can get creative having multiple emitters in a room rather than one big one and also going up to 700mm rather than 600mm etc. Lots of ways to skin the cat. 

 

Plumbing them top bottom opposite ends gets you an extra 5% over the usual BBOE.

[IGP]

32 minutes ago, IGP said:

9.5kW for 70m2 seems awfully high. I’d be interested to know how much of that is assumed ventilation losses. 

Doh yes 5.5kW, not 9.5kW! 
 

And mad they’re specifying such a large HP! 

[JohnMo]

2 minutes ago, IGP said:

Doh yes 5.5kW, not 9.5kW! 
 

And mad they’re specifying such a large HP! 

So in reality you need a heat pump that do 6kW at your design temp, this will allow two hours for DHW, (2x 1 HR slots) while also supplying all your heating demand

[Dave Jones]

does seem to be OTT size but then its going to be a rip off MCS installer so to be expected.

 

our new regs new build heating requirement came out at 29w / m2 with a -15C outside temp less than half of that at zero when i did the initial calcs, actual performance is a little better.

[PhilT]

47 minutes ago, Dave Jones said:

does seem to be OTT size but then its going to be a rip off MCS installer so to be expected.

 

our new regs new build heating requirement came out at 29w / m2 with a -15C outside temp less than half of that at zero when i did the initial calcs, actual performance is a little better.

m2 for what, just the floor area or every part of the internal surface area, floors, walls and roof ceiling?

[ReedRichards]

18 hours ago, Dave Jones said:

any flow temp 40c+ is going to painfull to run.

 

16 hours ago, JohnMo said:

Flow temp is a joke, push for 35 degs

 

16 hours ago, IGP said:

Also yes that’s a high flow temp, very painful

 

What you are trying to achieve is the best compromise between (maximum) flow temperature and radiators you can fit in the available space.  The lower you can make the flow temperature, the more economical your ASHP will be to run but the larger will be the surface area of the radiator(s) needed to heat each room.  A radiator specified to run at an average of 15 degrees above room temperature needs to be 2.5x bigger (in surface area, essentially) than one specified to run at an average of 30 degrees above room temperature.  The latter is roughly what you would have with a 53 C flow temperature.

Edited August 29 by ReedRichards

[ReedRichards]

18 hours ago, TheMitchells said:

I believe the calculation shows that the bungalow will need 13,350kW to heat the place. But the total electricity used last year for the whole place was less than 12,000kW so is their heat demand calculation incorrect?

You mean kWh but yes, it means that the heat demand calculation is either wrong and/or it's based on keeping the house warmer than you actually do and/or last year was milder than the calculation suggests.  Most of your electricity usage will have been for heating and hot water and I don't think these calculations ever agree perfectly with actual numbers.  

[ReedRichards]

For some reason I'm not able to download the pdf files attached above.  Is there a trick to do that?

[Dave Jones]

22 minutes ago, ReedRichards said:

 

 

 

What you are trying to achieve is the best compromise between (maximum) flow temperature and radiators you can fit in the available space.  The lower you can make the flow temperature, the more economical your ASHP will be to run but the larger will be the surface area of the radiator(s) needed to heat each room.  A radiator specified to run at an average of 15 degrees above room temperature needs to be 2.5x bigger (in surface area, essentially) than one specified to run at an average of 30 degrees above room temperature.  The latter is roughly what you would have with a 53 C flow temperature.

 

can allways use fancoils if space limited, double as AC in summer as well.

[ReedRichards]

13 minutes ago, Dave Jones said:

can allways use fancoils if space limited, double as AC in summer as well.

I would be surprised if you can get a quote for fan coils as part of the installation.  As it's a retrofit you could not use them for Air Conditioning without planning permission.  And you have to not mind the fan noise.

[Dave Jones]

3 minutes ago, ReedRichards said:

I would be surprised if you can get a quote for fan coils as part of the installation.  As it's a retrofit you could not use them for Air Conditioning without planning permission.  And you have to not mind the fan noise.

yeah i dont think you know what a fancoil is. 

 

you dont need planning permission for hanging a rad lol.

 

 

[ReedRichards]

If you retrofit an ASHP then under many circumstances it qualifies as a Permitted Development.  But that only applies if you don't use it for cooling.

  

Of course if it is part of a new build then the planning permission will encompass the heat pump and you can do what you like with it, heat or cool.  I presume @Dave Joneswas in that situation so his ignorance can be forgiven.     

[Dave Jones]

9 minutes ago, ReedRichards said:

If you retrofit an ASHP then under many circumstances it qualifies as a Permitted Development.  But that only applies if you don't use it for cooling.

  

Of course if it is part of a new build then the planning permission will encompass the heat pump and you can do what you like with it, heat or cool.  I presume @Dave Joneswas in that situation so his ignorance can be forgiven.     

 

yeah right lol the software police will come and make sure you dont press the 'cooling' button as that is the only difference in the setup.

[LnP]

1 hour ago, Dave Jones said:

 

yeah right lol the software police will come and make sure you dont press the 'cooling' button as that is the only difference in the setup.

I agree you're unlikely to get found out, but you should think about the possibility that neighbours complain about noise from the ASHP running all day on cooling mode in summer when they have their windows open. If they dob you in to the council you might have a problem.

[JohnMo]

4 minutes ago, LnP said:

I agree you're unlikely to get found out, but you should think about the possibility that neighbours complain about noise from the ASHP running all day on cooling mode in summer when they have their windows open. If they dob you in to the council you might have a problem.

I would doubt they would even realise, they make so little noise doing cooling, especially if you are flowing 14 to 16 degs Mine just runs at the lowest it can modulate, can't it hear it from about a metre away.