Tim S

Planning stats as limit switches, mixer on manifold as over temp safety, no buffer as it’s an insulated slab of 35 ton mass, I’ll run weather comp from the FTC2BR if can get the blasted thing to stop depowering the circ pump…… hence my question…!

Hi everyone. My heat pump is a 5kw Ecodan with FTC2BR bought as package. Stats, manifold, wiring centre are Wunda. The sparky (who has since done a Mitsubishi installer course) says the FTC, shortly after start up, commands the circulation pump off, which then causes the heat pump to shut down as there is no flow. This happens on both DHW and UFH cycles. System uses a zone valve each rather than a 3 way valve. Has anyone had a similar experience with the FTC2BR or could offer any insight into why the circulation pump is being commanded off? Mitsubishi technicals response to my sparky was basically 'bin the controller and buy an FTC6' which obv I’m not exactly happy to do…!

Interesting. Mitsubishi technical pre sales told me that their Ecodan monoblock does not have a built in circulation pump. Then again, they also told me that the FTC2BR controller had to be used with a BEMS system. Doesn’t particularly inspire confidence! I had originally planned to use it as you say for cylinder heating, and Wunda specced and supplied another pump on the manifold for the ufh side. It is possible I would need an extra pump on the dhw as I’m using two towel rails teed off it to run at the higher temp than the ufh temp for early morning and evening bathroom temp boost and the pipe runs are quite long….

Hi Johnmo yes the wiring centre appears to have one volt free or 230v output. However there will be two pumps and zone valves, one each for dhw and UFH, so I was wondering how the second one is switched? No liquid buffer, but it’s a pipes in slab UFH arrangement, so the 35 odd tons of concrete should buffer pretty well I would have thought… cheers

Hi everyone. the lengthy saga of my ashp installation continues! Thanks to everyone who messaged me or otherwise had suggestions for getting the electrical side done. I am possibly sorted now, but the sparky has been a bit wary of the whole process. I’ve settled on a 5kw Ecodan with the FTC2BR controller and am using Wunda H box wiring centre / manifold etc I remember on here somewhere there being a discussion about incorporating relays into the system but I can’t remember where. Could anyone direct me to the thread or possibly give me a steer as to whether I need to check the sparky has thought about this? Many thanks Tim

Great. Correct, basic mechanical. I was wondering about the usefulness of this, but it makes sense to use it as overheat protection. Again correct, no rads, just UFH. Big thanks for your input, very helpful.

Ok, now I am really confused, as I phoned Mitsubishi UK pre sales to find out the difference between the two and the man said that if I went for the FTC2BR I would have to buy a BEMS system and that that was way more complicated and expensive, and to go for the FTC6. I was wondering why the FTC2BR was available as a package if it was so specialised…! I ideally want to do what you suggest - use a fairly simple controller, zone stats as coarse control, mixing valve as a safety in case of over temp and use the slab as the buffer (not sure if you twigged the other thread about having problems getting in the trades to fit it all was mine btw). I’ll get back in to the manuals tonight and see if I can make some sense of it all…

Thanks for the replies everyone. The plumber's tame sparky seemed a nice enough guy, then quoted £1850! The next sparky just pulled out as he looked at the Ecodan installer manual and said it was too confusing - 'get a Mitsubishi accredited installer'! Hence my post! The installation is a 5kw Ecodan with UFH in an active slab of 37 tons mass, so should be an ok buffer as is. It’s a detached 1000 sq ft building, and I’ve used the Ubakus spreadsheet to analyse the heat demand. It’s all pretty routine I would have thought. I would have had a go myself (wired a car from scratch before) but I just don’t have time. Regards all

Hi Steamy, I'm in a village about 3 miles from Aylesbury as the crow flies. I'm sure the price goes up as soon as any trades drive into the village!

Hi everyone. I'm finishing off a granny annexe build (anncillary building hence no ASHP grant) and having a nightmare getting the ASHP etc done. My folks are supposed to be moving in in 3 weeks! I've contacted about 30 firms. MCS ones either aren’t interested or want 15k, normal plumbers and sparkles just haven’t been returning my calls or aren’t interested. If anyone can help with a non MCS installer who doesn’t want a grand a day, or an electrician who would be happy to wire in an Ecodan and FTC6 controller, I'm all ears. i do have a plumber teed up for about 600 per day but that’s the non electrical work only. I can’t find a sparky to do the electrical side, and I,m pretty much at my wits end with this tbh…. if anyone can help I would be very grateful. Regards all Tim

Hi everyone. Background : plumber installing self specced ashp / UVC next week. No grant available so no MCS install as they are a rip off. Hi everyone, I’ve got myself confused over what Mitsubishi controller does what. I’m aware the two options for controlling an Ecodan are the FTC6 and the FTC2BR, I’ve read the Mitsubishi info on both, but it’s clear as mud to me which one I need. system is 5kw Ecodan on S plan architecture for UFH and DHW, no rads. Non Mitsubishi UVC due space restrictions and budget constraints. I got a package from Wunda including room thermostats (4 zones) and their H box wiring centre. Wunda designed the pipe installation and I’ve analysed the heating demand on one of the spreadsheets used by forum members on here. It’s a part self build, so the thermostats are already in. However, it seems that since i bought the kit from Wunda about 3 years ago, the philosophy of how to manage the heat pump has changed, and I would like to embrace weather compensation/ setback etc, and am also wondering if the H box wiring centre is needed…. Can anyone advise me which controller would be best, which will work with the third party thermostats, cylinder, Wunda H box wiring centre (do I even need this)but allow me in due course to use weather compensation etc. Thanks in advance, and apologies for asking a numpty question!

Thanks everyone. Re air changes per hour, I don’t know what they will end up at, as it’s a barn conversion. The (German) heat modeller had a variety of ACH options so I ran best and worst case, 0.7 and 2, and the weather extreme was worst case too at -10c, unlikely to see that often in Bucks where we are. it’s looking like a 6kw ashp will have us covered and will tick over nicely most of the time. Whether or not we need a buffer is another question. Our 16mm pex al pex pipes are about 680 m….

Hi everyone, I’ve been a lurker on here for some time and have found it a great source of info. im hoping to get some help here as I have to specify an ASHP for our barn (granny annexe) conversion, but despite a lot of time spent here and googling, I have some possibly daft questions to ask…! So here goes: I have a Wunda supplied UFH kit (no rads). They advised me that my peak heat requirement was 4.9 kW, and I have run a calc (having calculated U values etc) which gave peak requirement -10 outside, 20C inside target temp of between 3.9kW at 0.7 ACH and 6.9 kW at 2 ACH (ie windows left open). What output ASHP do I need, with a normal occupancy of 2 people in the annexe (so I thought 200lt HW cylinder plenty). Also, for the DHW heating, do (or rather, can) ASHPs switch to a higher output temp than when they are running the UFH only. I see COP reduces with increased output temp, so can I have the pump ticking over for the UFH and then once a day crank it up for HWcycle? If anyone wants to suggest a particular ASHP or good source to buy one please feel free. My head is exploding with all the options and all the decisions I am having to make at the moment - got 2 hrs sleep last night worse luck! Thanks in advance Tim PS the build is tight on budget so value recommendations doubly welcome!