My DIY installed Vaillant AroTherm Plus is now LIVE

Live link to my system data - https://emoncms.org/app/view?name=championc&readkey=5e5a2bd11d69740be46a55e1793e551d

Well, after months of planning, research (between blogs, FB posts and YT videos), my Vaillant AroTherm + is now Live and up and running. While there is no Irish support, Vaillant Technical Dept in the UK have been very helpful with queries, and the UK FB group is very active, with several of the prominent YouTuber installers and users on there too. And of course, the Vaillant is always up there at the top of the www.heatpumpmonitor.org charts. The potential for running the AroTherm at higher temperatures, given that it’s R290 Propane based, meant that I could, in theory, run at gas boiler temperatures, if push comes to shove.

Overall, it has been a fairly painless experience.

We have a 3 bed Semi-D in Sth Dublin. We currently have a Vaillant Combi non-condensing non-modulating Gas boiler (so only around 60 – 65% efficient). I figured that evening running the AroTherm + at high temperatures, I would still have better efficiency. We also have a 30 Tube Kingspan Solarmax solar tubes installation since 2012. The tank has no spare coils and with the Kingspan working very well, it made sense to leave well enough alone.

Last November, I started using the MyEnergi Eddi to heat water to 60 deg overnight (on 5c/kWh Pinergy was a no-brainer). The tubes did an additional topup during the day on good days. If necessary, I could boost with the MyEnergi app in the evening if required. This meant I could stop using Gas and the Combi for DHW, and that worked very successfully over last winter. I had also lowered the CH Max flow temp as a way of understanding how a lower rads temperature might work out.

Therefore, the DHW requirement (and associated potential pipework) was removed completely from the plan. We currently use the Tado system with electronic TRV’s on all rads. We don’t heat all rads all of the time currently, but I am open to including more usage of ones which are currently less used. While efficiency is important, I want to run economically (even at the expense of efficiency). With no UFH, it made sense not to install a buffer tank. With sufficient capacity in the rads for defrosting too, there was no need to have to consider adding a volumizer either.

So the AroTherm flow and return would simply be T’d into the existing rads circuits.

I started with doing a heatloss calculation using https://heatpunk.co.uk and concluded I needed a 5kW unit, especially since I knew I still wouldn’t be heating the whole house constantly. Mind you, I was pretty certain of this size, based on blogs and YT videos for similar properties.

The first decision was the outdoor unit location. I had considered locating it in the side passageway, backing straight onto the wall of the combi. But it would have been blowing straight onto the neighbours house side wall, and would have narrowed the access considerably, since I will likely wrap the house next year, and so that would reduce the gap by a further 100mm. Airflow between both houses wouldn’t have been great either. So I went with the back garden, backing onto the boundary wall. I used M10 bolts screwed into zebedee’s for mounting and levelling. It is very important for the unit to be perfectly horizontal and vertical is all directions

The next decision was the arrangements of the pipework accessories. I got an Inta 1 ¼” to 1” valve for the flow, and an Impel 1” Filter & Mag valve on the return after a 1 ¼” to 1” reducer, with 1” Flexi hoses. I also got a 1” Anti-Freeze valve and a 1” Fill & Flush valve ( https://www.heiz24.de/Flushing-and-filling-unit-DN-25-1-internal-thread-2xKFE-12-NEW - a fantasic buy). I ended up putting the Filter, Anti-Freeze and Fill & Flush in series, after the Flexi hose.

Threaded joints are an absolute nightmare. However, when in Chadwicks, a Polish customer recommended Sellador thread locker. It was absolutely brilliant. So no tape anywhere – used this on ALL threaded joints.

From there, it was 1” copper all the way into the house. The pipes are lagged with Primary Pro insulation, which took some amount of tracking down to get (https://spares-direct.co.uk in Belfast). But it is far superior to the €1 per meter crap.

Inside the house, a pair of 1” x ¾” x ¾” 318’s linked the new 1” incommer into the upstairs and downstairs ¾” circuits. My main sitting room and hall rads branched off the dining room, over ½” pipes. I needed to add another rad into the sitting room, so this section of pipework had to be upgraded to ¾” or I could have ended up with flow issues. So while it was a pain, it was the proper thing to do.

So a last word on the Copper pipework. I am sorry I didn’t get “tectite” ( https://www.pipelife.ie/plumbing-systems/plumbing-heating-fittings/tectite.html ) push fittings.

The 1” compression joints were an absolute nightmare to seal fully. I had to use PTFE tape on several of the olives. The Fill & Flush became invaluable, being able to pressurise and leak-test pipe sections (once you capped off both ends and have a pressure gauge connected), or being able to almost flush the whole system through at will, especially to flush through a single rad if required (by closing all others).

I also bought Climaflex for insulating the indoor underfloor pipework https://www.amazon.co.uk/Climaflex-Pipe-Insulation-Foam-Lagging/dp/B07FMC58NB

The electrical connections are very straight forward. There are two wires needed for the outdoor unit – a 2.5mm T&E for the AC power, and a 2 wire 0.75mm cable for the eBus, linked back to where you locate the indoor controller.

I bought the SensoComfort Wireless Controller VRC 720f/3, who’s receiver is also linked to the ebus. I also bought an https://ebusd.de dongle, to extract all of the data locally from the system, for feeding into Home Assistant (and to upload data to heatpumpmonitor.org). It is USB powered, which I powered from a mains to USB adapter https://www.aliexpress.com/item/1005007009749779.html?channel=twinner , which I then buried inside the controller itself. I ran a spare Cat5 out to the outdoor unit, but I don’t see an immediate need for it.

I also linked my TADO Extension Kit controller to a port on the indoor controller, which enables the TADO to control the On/Off of the Heat Pump. The Extension Kit can do a Potential Free NO or NC connection.

As a cheap extra option, while doing the install, I bought and installed the Cooling Plug to enable to cooling function of the unit. This one is about £7 (part No. 0020266328) and is officially for a Vaillant Gas Boiler, but it works perfectly. The official AroTherm one is over £300 – go figure !!!