Omi Posted May 17, 2021 Share Posted May 17, 2021 Hello, We are installing an ASHP system for UFH and DHW but have a bit of a challenge fitting in a reasonably sized cylinder. The space allocated for this is under the staircase but that's obviously presenting some height challenges. Speaking to the supplier, they think a 170L cylinder will fit given the height constraints but I was wondering if it's possible to have secondary tank in parallel to increase the overall capacity of the system? I have asked the supplier the question but haven't had a response yet. A quick search on the web shows that it's definitely possible for traditional boiler systems but wondering if anyone has done this for ASHP systems? We're looking at the Mitsubishi ecodan ASHP + preplumbed cylinder systems and the cylinders look pretty complicated with quite a bit of electronics on them. So I'm wondering whether it's possible to have the ecodan cylinder as the "primary" with another 3rd party cylinder as a "secondary"? Thanks for any advice on this. Link to comment Share on other sites More sharing options...
joe90 Posted May 17, 2021 Share Posted May 17, 2021 @Nickfromwales is your man, he will be along shortly......... 1 Link to comment Share on other sites More sharing options...
Carrerahill Posted May 17, 2021 Share Posted May 17, 2021 (edited) 35 minutes ago, Omi said: Hello, We are installing an ASHP system for UFH and DHW but have a bit of a challenge fitting in a reasonably sized cylinder. The space allocated for this is under the staircase but that's obviously presenting some height challenges. Speaking to the supplier, they think a 170L cylinder will fit given the height constraints but I was wondering if it's possible to have secondary tank in parallel to increase the overall capacity of the system? I have asked the supplier the question but haven't had a response yet. A quick search on the web shows that it's definitely possible for traditional boiler systems but wondering if anyone has done this for ASHP systems? We're looking at the Mitsubishi ecodan ASHP + preplumbed cylinder systems and the cylinders look pretty complicated with quite a bit of electronics on them. So I'm wondering whether it's possible to have the ecodan cylinder as the "primary" with another 3rd party cylinder as a "secondary"? Thanks for any advice on this. Fit 2 x Sunamp units. We had the rep in last week and took us through all the options. Quite clearly 2 unit (I think they were the 9kW units equivalent to 210litres) around the size of a washing machine would replace having two large cylinders and she said they could be installed on shelves so one above the other?!? Are the Mitsi units not low temp? Edited May 17, 2021 by Carrerahill Link to comment Share on other sites More sharing options...
SteamyTea Posted May 17, 2021 Share Posted May 17, 2021 9 minutes ago, Carrerahill said: 2 x Sunamp units. 1 They won't work with an ASHP. 2 They won't work. 3 They will stop working. Physics wise, the thermal losses will be higher than a single cylinder. Is there enough room to 'box them in' with insulation? 1 1 Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 17, 2021 Share Posted May 17, 2021 2 hours ago, SteamyTea said: They won't work with an ASHP. They do now, apparently. But beware ill-informed over-eager sales folk 2 hours ago, SteamyTea said: They won't work. The latest iteration seemed to be a nice offering, but 2 out of 3 I fitted for a client failed, after they replaced the 3 that failed before them. SA acted swiftly and reasonably in the replacement of the units, but it was a mammoth undertaking, and a royal PITA for the client. 2 hours ago, SteamyTea said: They will stop working. It's largely down to correct 'model' selection, and adequate sizing, as to how reliable an installation will be. The newest have no real reason to fail, but boffins continue to expect to manipulate and examine these under microscopes vs just plugging them in and walking away from them, which is what SA NEED you to do in order to succeed. 2 hours ago, Carrerahill said: she said they could be installed on shelves so one above the other?!? That will be one MF of a shelf....... I think SA recommend sitting one directly on top of the other, but a bit of a ball-ache then to lift the lid off the lower unit to access the electronica. These would best be fitted on bespoke 1" box steel frames so the upper unit sat at least 150mm above the lower unit. These would need to be UBER robust, and bolted back to the wall with some BFO bolts, because if that ever toppled over it would kill anyone it landed on. Best you go pick a size 9 up and see what you think about the 'one over' option..... Why dont you just go for a single 12? 270-280L DHW equivalent size is quite substantial for a domestic setting. Link to comment Share on other sites More sharing options...
Omi Posted May 17, 2021 Author Share Posted May 17, 2021 @Nickfromwales - any suggestions regarding the original question? If I wanted to go with 2 cylinders rather than the sunamp kit? Thanks! 3 hours ago, Carrerahill said: Are the Mitsi units not low temp? They are but they contain an immersion heater for a weekly boost to 60 ℃+ to kill off any bacteria. Link to comment Share on other sites More sharing options...
Scoobyrex Posted May 17, 2021 Share Posted May 17, 2021 We had a quote for a Panasonic ASHP with two hot water tanks, 1 for the master bedroom, kitchen, cloak room, laundry room, utility, the other for 2 further ensuites and the master bathroom. 1 Link to comment Share on other sites More sharing options...
Omi Posted May 17, 2021 Author Share Posted May 17, 2021 4 minutes ago, Scoobyrex said: We had a quote for a Panasonic ASHP with two hot water tanks, 1 for the master bedroom, kitchen, cloak room, laundry room, utility, the other for 2 further ensuites and the master bathroom. Thanks - good to hear that it might be possible. Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 18, 2021 Share Posted May 18, 2021 12 hours ago, Scoobyrex said: We had a quote for a Panasonic ASHP with two hot water tanks, 1 for the master bedroom, kitchen, cloak room, laundry room, utility, the other for 2 further ensuites and the master bathroom. Hi. With an ASHP, the heat output is nowhere near the amount of energy of a gas boiler for eg, so the flow needs to go to a single discipline at any one time to allow a cylinder to reheat in a 'reasonable' time. DHW output from the ASHP in the above quote, I assume, would be dire if the cylinders were attempting to heat in parallel, unless it was a larger, high temp unit producing the required heat. Do you have the particulars of the quotation / design proposal? High temp split unit / other? I think that would become far more problematic with 2x smaller size UVC's due to the inability of the end user to 'share' the stored energy equally amongst the occupants. I could see the ASHP chopping from UVC to UVC and ignoring the heating for extended periods here, and with radiators that would be notable. A setup with a decent slab with UFH may have less issues there. Could anyone here comment on how long a, say, 9kW ASHP takes to fully recharge a 300L UVC from, say, 70% depleted? @PeterW ? 12 hours ago, Omi said: @Nickfromwales - any suggestions regarding the original question? If I wanted to go with 2 cylinders rather than the sunamp kit? Thanks! Concerns, as per the above. The SA wins on form factor, and a single size 12 unit would suffice for most domestic settings, however the ASHP would need to run out of its 'comfort zone' to get beyond the melting point of the SA PCM and the CoP would be worsened accordingly. Acceptable to some as an off-set to the Balancing the flow from 2 UVC's would be the challenge, eg so that one doesn't run cold and start blending the max hot water temp from the combined output, so that solution would only really be viable if the UVC's were in series or the UVC's were identical in size and the cold inlet and hot output pipework were hydraulically similar at / from relative T connections. If the stairs are sloping, then the assumption would be that the second cylinder would be half the capacity, or less, so in this instance the series connection setup would be the only option. Ok, is there any option to increase the size of the space at / under the stairs at all? Maybe with a stud wall moving etc? 1650x660mm would get you up to 300L. Link to comment Share on other sites More sharing options...
SteamyTea Posted May 18, 2021 Share Posted May 18, 2021 25 minutes ago, Nickfromwales said: Could anyone here comment on how long a, say, 9kW ASHP takes to fully recharge a 300L UVC from, say, 70% depleted? FFS, you can calculate that. Link to comment Share on other sites More sharing options...
PeterW Posted May 18, 2021 Share Posted May 18, 2021 15 hours ago, Omi said: They are but they contain an immersion heater for a weekly boost to 60 ℃+ to kill off any bacteria. Not requried 1 hour ago, Nickfromwales said: Could anyone here comment on how long a, say, 9kW ASHP takes to fully recharge a 300L UVC from, say, 70% depleted Assuming 70% at 18°C and a target of 56°C then it is circa 70 mins assuming a 9kW ASHP at full chat 1 hour ago, Nickfromwales said: Balancing the flow from 2 UVC's would be the challenge, eg so that one doesn't run cold and start blending the max hot water temp from the combined output, so that solution would only really be viable if the UVC's were in series This is as per design I would recommend and use a diverter valve on the exit of the primary UVC. When it is returning the cooled return to the ASHP then in tandem mode it would return via the second tank. Simple way to do this is with a switch to provide an alternate route for the thermostats to trigger the ASHP. Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 18, 2021 Share Posted May 18, 2021 1 hour ago, SteamyTea said: FFS, you can calculate that. As my dad always said, if you've nothing good to say.........and it's a little tricky to calculate something when you're getting into a vehicle and driving from that point. Some of us aren't retired, remember 31 minutes ago, PeterW said: Assuming 70% at 18°C and a target of 56°C then it is circa 70 mins assuming a 9kW ASHP at full chat Thanks, dad. Link to comment Share on other sites More sharing options...
SteamyTea Posted May 18, 2021 Share Posted May 18, 2021 0.001167 kWh/litre.K / kW Link to comment Share on other sites More sharing options...
Carrerahill Posted May 18, 2021 Share Posted May 18, 2021 18 hours ago, Omi said: @Nickfromwales - any suggestions regarding the original question? If I wanted to go with 2 cylinders rather than the sunamp kit? Thanks! They are but they contain an immersion heater for a weekly boost to 60 ℃+ to kill off any bacteria. I was thinking more from heating a cylinder point of view... whereas Sunamp will work on lower temps. Link to comment Share on other sites More sharing options...
Omi Posted May 18, 2021 Author Share Posted May 18, 2021 4 hours ago, Nickfromwales said: Ok, is there any option to increase the size of the space at / under the stairs at all? Maybe with a stud wall moving etc? 1650x660mm would get you up to 300L. Unfortunately, no. I had been playing around with a model of the understairs cupboard which shows that it should be possible to fit in a 210L cylinder but the piping to/from still poses a challenge: The supplier mentioned that they could fit a 170L in the half-height space under the stairs so I was thinking of maybe combining that with a smaller (90L?) UVC. If it goes in series, I guess the hot water outlet from the ecodan cylinder would go into the cold water intake of the smaller cylinder with its hot water outlet servicing the actual demand? I guess the problem here is keeping the water in the second tank warm? Thanks. Link to comment Share on other sites More sharing options...
Carrerahill Posted May 18, 2021 Share Posted May 18, 2021 21 hours ago, SteamyTea said: 1 They won't work with an ASHP. 2 They won't work. 3 They will stop working. Physics wise, the thermal losses will be higher than a single cylinder. Is there enough room to 'box them in' with insulation? We have been told they will - in fact we were given a solution to a ASHP system in a residential development with limited space in the flats, by Sunamp. I am not a mechanical engineer so I will not dive in any deeper or pretend to know more other than to say, I am certainly being lead to believe they will. Link to comment Share on other sites More sharing options...
PeterW Posted May 18, 2021 Share Posted May 18, 2021 Horizontal tank will go in there - 300 litre too Link to comment Share on other sites More sharing options...
SteamyTea Posted May 18, 2021 Share Posted May 18, 2021 3 minutes ago, Carrerahill said: We have been told they will See Nick's reply higher up. 3 minutes ago, PeterW said: Horizontal tank will go in there - 300 litre too Seems an easy solution. Link to comment Share on other sites More sharing options...
Omi Posted May 18, 2021 Author Share Posted May 18, 2021 1 hour ago, PeterW said: Horizontal tank will go in there - 300 litre too 1 hour ago, SteamyTea said: Seems an easy solution. Maybe not - yes, physically it will fit but at least the ones I've seen seem to be only for DHW? The ecodan cylinder provides both DHW and heating circuits (UFH). Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 18, 2021 Share Posted May 18, 2021 ( are we sure there is a horizontal HP UVC? ) Link to comment Share on other sites More sharing options...
rbw Posted May 18, 2021 Share Posted May 18, 2021 (edited) 1 hour ago, Nickfromwales said: ( are we sure there is a horizontal HP UVC? ) I think Telford do one... https://www.telford-group.com/product/horizontal Brand Telford Lead Time 2 - 5 working days Capacity (litres) 300 Heating type Indirect Immersion 1 x 3kw Water supply Unvented Height (mm) 650 Width (mm) 1650 Depth 550 Warranty Lifetime edit - just seen the requirements to handle UFH circuit too so ?♂️ Edited May 18, 2021 by rbw Link to comment Share on other sites More sharing options...
Nickfromwales Posted May 18, 2021 Share Posted May 18, 2021 1 hour ago, rbw said: I think Telford do one... https://www.telford-group.com/product/horizontal Brand Telford Lead Time 2 - 5 working days Capacity (litres) 300 Heating type Indirect Immersion 1 x 3kw Water supply Unvented Height (mm) 650 Width (mm) 1650 Depth 550 Warranty Lifetime edit - just seen the requirements to handle UFH circuit too so ?♂️ I don't think that has a HP coil in it. The stated range of HP UVC's all appear in the 'upright position'.... I'll ring Trevor tomorrow and get some inside information. Link to comment Share on other sites More sharing options...
rbw Posted May 18, 2021 Share Posted May 18, 2021 39 minutes ago, Nickfromwales said: I don't think that has a HP coil in it. The stated range of HP UVC's all appear in the 'upright position'.... I'll ring Trevor tomorrow and get some inside information. just saw this and assumed it was suitable... “Complete with high surface area coil for Heat Pump“ 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted May 18, 2021 Share Posted May 18, 2021 (edited) 4 hours ago, Omi said: The ecodan cylinder provides both DHW and heating circuits (UFH) Ah, why would you do that. Space heating and DHW are different things, they work at different temperatures, and different times. Have you actually done an analysis of your DHW needs? Edited May 18, 2021 by SteamyTea Link to comment Share on other sites More sharing options...
Omi Posted May 18, 2021 Author Share Posted May 18, 2021 9 minutes ago, SteamyTea said: Ah, why would you do that. Space heating and DHW are different things, they work at different temperatures, and different times. It's a dual-zone (DHW/Heating) cylinder so I imagine it is able to maintain them at different temperatures? It looks like a pretty complex piece of kit when compared to a "normal" indirect UVC: https://les.mitsubishielectric.co.uk/products/heating/domestic/cylinder/ecodan-ftc6-monobloc-pre-plumbed-standard-cylinder The white box is some kind of controller and there are separate pumps for the primary, DHW, and heating circuits. Link to comment Share on other sites More sharing options...
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