Split ASHP disadvantages

[Nickfromwales]

3 hours ago, DamonHD said:

Two near identical houses walking distance from here, have had identical ASHPs put in.

 

One had the external unit mounted directly on the exterior wall.  The other insisted on it being some way down the garden.

 

Latter house gets about half the CoP of the former...

 

Rgds

 

Damon

Got to be a crap install to half the CoP. The low loss pre-insulated pipe is very good, as long as it’s integrity isn’t compromised ( outer sheath punctured and then the internal pipes get water logged / poor detail at terminations etc. 

[rbw]

2 hours ago, zoothorn said:

If you are determined to have one, Id strongly suggest fitting the boiler & cylinder as far away as possible/ farthest corner of house (& in a soundproofed enclosure too, seriously).

 

The reason I think these are dished out foc (as mine has been so at least I'm not £10k out of pocket) is bc they aren't designed adequately enough to tamp the noise. No pdf info on any dB considerations for the inside units.. is fishy to me. When I saw the boiler sides clad in cheap black styrofoam.. & was told 'its sound insulation' once it was being fixed to my spare bedroom cupboard wall.. my alarm bells rang, but too late & I just had fingers x'd etc. But my worst fears have been passed in last 2 days. I cannot have this tmrw 6.45, so this ev I'll have to turn the whole system off.

Thanks for relaying you’re experiences @zoothorn sounds like this unit is definitely one to avoid. That said, as mentioned earlier. my indoor unit will be in a basement with 200mm solid concrete, 100mm insulation, UFH board, UFH and then flooring in top. I doubt noise would actually be an issue in this case with a decent unit that has been correctly installed.

 

Interestingly both Daikin and LG do quote sound levels for their indoor units, both at 28dB. No idea whether this is what is achieved in real world usage though. 

[rbw]

1 hour ago, simon45089 said:

I am planning to site a Mitsubishi ecodan (monobloc) ashp unit 25 metres from the compatible Mitsubishi cylinder which will be in the house,  to minimise any intrusive noise and due to the layout of my barn conversion. This week I confirmed with the mitsubishi technical chap that this would be fine and would not affect performance as long as insulated dual pipe was used to connect the ASHP to the cylinder. I have sourced the pipe through a company called Mibec.Its overall diameter is 125mm, with two 32mm pipes within. A 25 metre run with fittings is around £675.00 I think. The guy at Mibec said this is now a common approach and the pipe is very popular. Other manufacturers make it of course. He said heat loss over the 25 meters would be negligible.

After  reading comments above I hope what I have been told is true!  I queried the distance I am going for with the mitsubishi chap and said I thought I read somewhere in my research that the distance should be limited to about 12 metres. i think he said that was the case when the refrigerant was circulated, but now it remains in the ashp so distance is no longer an issue. The only proviso was that you may need an extra pump added to the system if the integral one cant manage on its own but by using 32mm pipes it may be fine. ( The minimum recommended pipe diameter for the ecodan is 28mm).

 

fantastic info, thanks @simon45089 I’ll be looking into this solution and seeing if it’s also valid for a split unit in which (I think) just the refrigerant is cycled between the outside and inside unit. But this now has me thinking that I could maybe just go for a monobloc unit and this pipe solution... hmmm...

[Nickfromwales]

46 minutes ago, rbw said:

Thanks for relaying you’re experiences @zoothorn sounds like this unit is definitely one to avoid. That said, as mentioned earlier. my indoor unit will be in a basement with 200mm solid concrete, 100mm insulation, UFH board, UFH and then flooring in top. I doubt noise would actually be an issue in this case with a decent unit that has been correctly installed.

 

Interestingly both Daikin and LG do quote sound levels for their indoor units, both at 28dB. No idea whether this is what is achieved in real world usage though. 

Set 4 M12 threaded bars into the basement slab where you intend to mount the internal unit. Sleeve the bars with self adhesive neoprene insulation tape to minimise cold bridging, and then finish laying the floor as per above. 
Then fit uni-strut to the bars and anti vibration mounts to that, then the unit. 

[simon45089]

Have a look on you tube at a site called "My Home Farm".  The guy on there- who I think has contributed to this forum, has  done what I plan to do. He is really helpful and has answered queries from me directly. He did an update a year after installation about the efficiency of his ASHP also on you tube. I find real life experiences really useful in my research, especially when the people involved are not trying to sell me anything. Its all a bit of a minefield, but I am seeing a way through I think !

Edited September 27, 2020 by simon45089

[rbw]

1 hour ago, Nickfromwales said:

Set 4 M12 threaded bars into the basement slab where you intend to mount the internal unit. Sleeve the bars with self adhesive neoprene insulation tape to minimise cold bridging, and then finish laying the floor as per above. 
Then fit uni-strut to the bars and anti vibration mounts to that, then the unit. 

Very timely advice @Nickfromwales as the basement slab is going to be poured on Thursday. Will definitely look into this, thanks. 

[rbw]

1 hour ago, simon45089 said:

Have a look on you tube at a site called "My Home Farm".  The guy on there- who I think has contributed to this forum, has  done what I plan to do. He is really helpful and has answered queries from me directly. He did an update a year after installation about the efficiency of his ASHP also on you tube. I find real life experiences really useful in my research, especially when the people involved are not trying to sell me anything. Its all a bit of a minefield, but I am seeing a way through I think !

 
Thanks @simon45089 - I was actually watching a few of those videos yesterday but not sure I saw the one year on video. That’s a big unit installed there, seemed to be quite noisy so not surprised it was located where it was. 

[joth]

12 hours ago, rbw said:

my indoor unit will be in a basement with 200mm solid concrete, 100mm insulation, UFH board, UFH and then flooring in top.

Is it a cold basement or do you have floor insulation under the basement slab too?

Only 100mm insulation really isn't much to put under ufh, you'll find a lot of energy escapes downward into the basement

[Onoff]

17 hours ago, Nickfromwales said:

Set 4 M12 threaded bars into the basement slab where you intend to mount the internal unit. Sleeve the bars with self adhesive neoprene insulation tape to minimise cold bridging, and then finish laying the floor as per above. 
Then fit uni-strut to the bars and anti vibration mounts to that, then the unit. 

 

On the assumption you don't have UFH pipes under the ASHP, couldn't he just drill into the slab later and resin fix 4 studs? Making damn sure if course he knows where the yet pipes are by measuring and writing down/photos beforehand?

[rbw]

7 hours ago, joth said:

Is it a cold basement or do you have floor insulation under the basement slab too?

Only 100mm insulation really isn't much to put under ufh, you'll find a lot of energy escapes downward into the basement

sorry @joth should’ve been clearer. Both basement slab and ground floor slab are 200mm concrete and both actually have 120mm rigid insulation board then UFH and flooring on top. 
 

 

Edited September 28, 2020 by rbw
Spelling

[ProDave]

Re the noise thing.  I wanted to avoid a split unit for 2 reasons, first is it requires an F Gas engineer to leak test and gas the system making DIY install not possible, but second the noise of an internal compressor.  Why would you choose to put a noise source inside the house when it can be outside in a monoblock unit?

 

The only noise we suffer is the water circulating pumps, which in spite of being one Grundfoss and 2 Wilo pumps are still audible as a low level hum, but you would get that with any wet heating system.  It was a lot worse before I changed the "no name" UFH pumps for Wilo ones.

[dpmiller]

I don't understand why the compressor isn't in the outdoor unit tbh...

[rbw]

13 hours ago, ProDave said:

 Why would you choose to put a noise source inside the house when it can be outside in a monoblock unit?

I guess when circumstances dictate that the outside unit needs to be placed a distance from the property. If this condition can be satisfied with a monobloc design without a significant loss of efficiency then great. That was the basic requirement outlined in the first post. 

[PeterW]

20 minutes ago, rbw said:

I guess when circumstances dictate that the outside unit needs to be placed a distance from the property. If this condition can be satisfied with a monobloc design without a significant loss of efficiency then great. That was the basic requirement outlined in the first post. 

Insulated pipework can sort this. Not that expensive tbh in the scheme of things. 

[rbw]

1 hour ago, dpmiller said:

I don't understand why the compressor isn't in the outdoor unit tbh...

It seems in split units this is actually the case, at least this is what it says in some Hitachi ASHP documentation:

 

Quote

 

The split units split the refrigeration process between the outdoor fan unit and the indoor unit. So, the compressor is in the outdoor unit and two pipes containing refrigerant connects to the indoor unit where the heat exchanger and water side is contained as well as the main controller.

The benefits of a Split unit is that the outdoor unit can be located further away from the property (typically up to 50m) with little or no heat loss. The outdoor units tend to be smaller and quieter.

 

 

But as others have pointed out insulated pipe can be used instead which seems a lot simpler. 

[zoothorn]

On 27/09/2020 at 12:02, rbw said:

 

 

Interestingly both Daikin and LG do quote sound levels for their indoor units, both at 28dB. No idea whether this is what is achieved in real world usage though. 

 

Thats very interesting.. lord if only Vaillant had: I have the ideal spot, well away from beds, I could have asked for my boiler/cylinder to be put!! I'm renovating it same time it was all installed! Im furious.

 

As to your OP header 'what problems', after a 3+ hour call to Vaillant (yup) I realise -another- problem with this system, certainly for me: regardless of the time settings block periods you can input for both heating & HW to come on between.. the heating comes on anyway. Day and night. Its just intrinsic to how the system works now I'm just told. IE right now my next block heating period is 6pm to 8pm. But the rads are on (& noise as I said too). I cannot possibly afford to run rads constantly during the winter, but it overrides my decision to ask them come on for 2 hours am & pm... & puts the rads on any time during 24 hr period too (& never when I know when)!! so I am on constant tenterhooks now about this noise.. which is nigh on constant right now (& its mild outside).

 

An utter disaster for me. I have had to agree to a £95 call out engineer on monday, altho its under guarantee, bc I have absolutely no other option (in case/ slimmest chance there -is- a problem with my boiler re. noise.. tho I know as its an electric pump doing it inside, its just highly likely the way its made/ nothing can ever be done to diminish it). Ruining my life this.

[zoothorn]

On 28/09/2020 at 21:56, dpmiller said:

I don't understand why the compressor isn't in the outdoor unit tbh...

 

It is, & this is a pump.. but its not the pump I'm referring to. Once it enters the house boiler via the high presssure pipes (eminating from the outside compressor- introducing noise into the house this does itself via these 2 big vibrating pipes), there's a pump in the boiler > pushing I assume the water into cylinder. This is the primary culpit.

 

ProDave is spot on as usual with his reply above. Lord alive I'm in such a pickle here. That's all I'll say as I've hijacked rbw's thread enough already.

 

zoot

[Onoff]

33 minutes ago, zoothorn said:

Ruining my life this.

 

You maybe one of those unfortunate people who are acutely sensitive to the vibrations of the dilithium crystals inside ASHPs. A strapadictomy might cure it. I'd ask the engineer when he comes.

[Pocster]

I talk to mine .

The big blue eye watches me .

[zoothorn]

9 minutes ago, Onoff said:

 

You maybe one of those unfortunate people who are acutely sensitive to the vibrations of the dilithium crystals inside ASHPs. A strapadictomy might cure it. I'd ask the engineer when he comes.

 

No. I am not. I fall asleep in front of my hfi belting out,  or dvd menu music blaring out I snooze thru & I wake at 2 am on sofa/ being middleaged now I snooze alot etc. As to a stridectomy I'll hav to look that up on the vaillant site.

 

As the moment what I need is a lobotomy. But you'll say Ive already had one Onoff (before you type it).

Edited September 30, 2020 by zoothorn

[zoothorn]

Sorry to harp on.. but more noise issues with my split ASHP. For some reason I'm noticing -alot- more outside compressor noise (the box outside) so much that I can hear it all around my house exterior in fact & very irritating too,  20m away its intrusive for eg, in one spot as its a vibration thing there are resonant frequency 'patches' where its really prominent. the fan is fine. Also some of this noise is being transmitted out & in through the windows (a floor above it) into my upstairs. So I have this damn compressor noise entering my house A) via pipes > boiler > transmitted along pipes > to cylinder, & now B) externally up & in through window. And a motor within the boiler noise too, totally separate/ often both in conjunction. Right now in kitchen I have an incessant background drone & its unliveable with. And the frequency of the damn thing firing up/ off/ on/ off will only ramp up when its cold.. its fairly mild now. Omfg.

[SteamyTea]

https://thehum.info/newhummap/html_docs/