Russdl

I’ve had another read through @Jeremy Harris’s thread and he noted that the latest Sunamp models are limited to 5 bar instead of the 10 bar of the previous variants, mine being one of those. After getting the expansion vessels to play ball I’ve got around 5.7 bar, which is around 2 bar above my known water pressure from when we started the build and, knowing what has happened to previous Sunamps, higher than what I wanted to see. I was curious so turned off the cold feed to the Sunamp. Pressure remained the same (trapped in the hot circuit). Ran a hot tap until it stopped which was only a few seconds - pressure dropped to 2.5 bar (I was expecting zero??) Deflated the expansion vessels - pressure dropped to 2 bar (was definitely expecting zero now!) I ran every hot outlet in the house, non of them ran apart from one shower (it was running cold so I guess that’s just cold water getting past the thermostatic mixer when full hot is selected?) Still 2 bar of pressure. I’m assuming my pressure gauge is knackered and miss reading by +2bar. Is that likely? If not, where is the 2 bar hiding and why can’t I get it out of my hot circuit? So, to recap I’m sat here with cold supply off, hot taps open, expansion vessels without air and showing 2 bar on the pressure gauge. Any clues??

@Dillsue good advice. At least one of my expansion vessels had effectively failed as there was no air in it. And I’m guessing there was nothing in the working expansion vessels as well hence the over pressure I saw. Now they are both charged up again everything looks fine - too my eyes at least.

No, there's no pressure relief valve in or around the Sunamp, and no mention in the MI's. I think I recall Jeremy's replacement Sunamp having some pressure relief facility that his previous set up didn't. I'll have to re-read that thread. It looks like getting the second expansion vessel working again has fixed my problem. There has been negligible change in the pressure after charging the Sunamp for a little over two hours. I guess my lesson learnt is that those little expansion vessels that are pretty much out of sight, shouldn't be out of mind. I'll add them to my list of things to check every 6 months to make sure they're holding they're charge. I don't think I've checked them once since we moved in.

I seem to have got the dodgy expansion vessel working again, they're both now charged to 3.5 bar and the Sunamp is on and charging in the daylight so I can keep an eye on the pressure.

@Dillsue I probably didn't make it clear but that is my view as well that the expanding water as the Sunamp heats up is causing the pressure rise. There is a non return valve on the cold mains supply, and on closer inspection it seems like only one of the expansion vessels is working properly. I can get air in/out of one of them, but not the other the other one. I guess those things break down? Would going from two 500ml expansion vessels to just one be enough to cause this big water pressure rise? I don't know. I don't think so. Can you throw any light on what that would look like and where I'd find it?

A bit of a long story: It transpires a joint in our DHW manifold has been dripping unnoticed for what would seem to be yonks. It drips onto a pipe directly below, that drip then tracks along the pipe to a water circulation pump and then drips off the back of that pump on to a pipe below it before finally hitting the wall leaving very obvious evidence, unfortunately that evidence is nicely hidden behind the Sunamp, hence it's gone unnoticed. After reading @Jeremy Harris recent woes I took a good look around mine and discovered the evidence of this leak. The trouble is, this leak only materialises when the Sunamp is charging, all other times the pipes are bone dry, initially it seemed to be the rear plastic moulding of the pump that was leaking as that was the only place where water was evident, it had long evaporated from the copper pipe work. I blagged a replacement pump off a friend and felt certain my problems were over, except that replacement pump seemingly started leaking in exactly the same place so I widened the search and eventually found the source. Throughout the days usage the joint remains bone dry, it's overnight when the Sunamp is charging that it starts to drip which lead to an unpleasant discovery. There is a pressure gauge on the cold supply to the Sunamp and early one morning I saw it indicating 13bar! Maximum operating pressure for the Sunamp is 10 bar. The pressure instantly reduces to around 5 bar when a hot tap is opened. If I isolate the cold supply and open a hot tap it reduces further to around 3 bar, but no lower. So every night (for years potentially) when the Sunamp charges the pressure builds to 13 bar and forces water to leak from an otherwise water tight joint in the DHW manifold (maybe this small leak has prevented anything worse happening?) What can I do about this? There are two 500ml expansion vessels fitted. Do I need another, larger expansion vessel? Is there something much bigger going on here? Any help gratefully received.

We used GRP angle attached to/cast into the slab for all our exterior doors. On our sliders I put 7 x 150mm M12 bolts through the GRP, threads extending into were the slab was going so that the bolts would be encapsulated in the slab when it was poured. It seems to have worked fine, no thermal bridge and enough strength to hold a big heavy slider. The slab was kept 25mm lower where the slider was going so that Compac Foam could be used under the sliding door threshold to insulate it from the slab. The front and back doors were much easier with their narrower thresholds. Sliders Front and back doors were simpler.

Don't! It'll be sweet, and if not it's really easy to clean. Let me know if you have any dramas when you getaroundtoit, splitting the fan casings and getting to the nitty gritty/mouldy slimy is really easy (when you've got the fan units out)

Probably right, I won’t be doing that for another three and a half years 😃

I took the extract fan housing to pieces, it was a bit grim on closer inspection but I was expecting a lot worse so I’m pretty chuffed and I don’t think I broke anything in the process which is a great result 😃 I’m pretty sure my pre filters have helped, and not turning the MVHR on until all the building work had ceased can’t have hurt things either. I’m wondering if the fact it’s an enthalpy unit helps as well? It was bone dry inside and I’m presuming there will always be some moisture inside a non enthalpy unit?

Got them out. So to remove the fan's I followed the instructions by giving a sharp tug and rotating the fan housing out (reversed for the fan on the other side). The next step in the instructions wasn't working for me without making me nervous of causing damage so I found that I could lift up the fan housing (orange arrow) by just a small amount which was enough to allow the rest of the steps to be followed without issue.

The manufacturers instructions for removing the fans make it look incredibly easy, the reality for me is that it isn’t, feels like I’m going to damage the polystyrene internals trying to get the fans out. Does anyone have any ‘top tips’ for the fan removal of a Brink Flair 400 MVHR (or anyone have superior Googling skills - I can’t find anything) ~~~ I’ve left it far too long to finally get around to cleaning my MVHR heat exchanger and fans (3.5 years!) but it looks like I’ve got away with it. Frankly I’m amazed how clean it is in there. The dirtiest component is the fan on the extract side which I guess is to be expected. Intake fan Extract fan

Yes, please do. It’s very interesting but complete Swahili to me. I would like to learn a new trick if you can spare the time (and start with the basics!)

I’ve got one in the garden on my weather station but annoyingly it quit recording the Solar Radiation a while ago. Consequently I’ve substituted Solar Radiation with PV Production so I can continue to bore my wife witless with my statistics. 😃

@JohnMo do you think you have a have problem then? We have had wall to wall sunshine down here for the last few days with hardly a cloud in sight so not at all atypical.

Significant difference down south. 27th Feb - 4th Mar 2024 26th Feb - 4th Mar 2025 The most noticeable result of the increased solar is the decreased heating requirement (the house is around 21 degrees). The heating last turned off at 05:30 on the morning of the 27th Feb and it hasn’t been back on since. It doesn’t look like we’ll need any this week and maybe not next week either despite negative overnight temperatures, down to around -4 to -5 on recent nights. Epic.

That’s a good point. We have zinc, formed on site and 600mm centres. 400mm would have looked better. Pigeon shite eventually doesn’t wash off completely either, so if you can get anti roosting wires/spikes fitted economically consider those as well.

@Onoff that is a genius suggestion. I’m now trying to find something around here that I need a Quinetic door switch for. @Pocster have you had a look at the videos on the product page in the link.

Thanks for that explanation @John Carroll much appreciated. 👍🏻

That's interesting, I've never seen temperatures even close to that after 6 hours of running. I've turned the pumps down as well to slow down the rate of flow, perhaps I need to turn them down further? I do have a 7°C temperature drop between flow and return which I believe is optimum. Out of interest, what size is your UFH system? Mine is 824 meters of pipe (no idea how many litres that equates too). @John Carroll Thanks for those figures. What is the maths, I can't work it out? That and @ProDaves comment certainly indicate that there is no benefit from isolating one of the Willis heaters, but the lived experience is different for whatever reason.

Wow, there's a lot of words up there. ⬆️ And some shouting. Just for the record I have no criticism of the physical installation in any way, it's a work of art. ~~~ I'm not sure how many people on here use Willis heaters for their UFH? I don't think there are that many of us? We only need one 3kW Willis heater to heat the house. We have two 3kW heaters plumbed in parallel. As someone who has lived with Willis heater UFH for a few years our experience is that having the water flow through 2 Willis heaters (one 'on' one 'off') mixes down the temperature of the water exiting the 'on' Willis heater. It would, wouldn't it. The water flows through the Willis heater at a certain rate (not exactly sure how many litres/min) but definitely not slow enough to get to any significant temperature before it's on its way around the system again. The highest exit temperature I've seen with a thermal camera is 34.2°C and that's after the UFH has been running for the best part of 6 hours (I set the thermal cut out to 40°C). At the beginning of those 6 hours it would have been around 22-23°C. The house copes very well with the one Willis heater providing the heat and, despite this January being unusually cold for us soft southern bastards, we've had a useful amount of sun to offset that and just running the one Willis heater has been fine. Anyway, as the prophet said "He's grown man so let him just carry on about his business please" and, as a grown man - I think I will 😃

Thanks for that, I don't think that document is relevant for the Willis heater arrangement but I appreciate the 'heads up'.

We have two Willis heaters plumbed parallel for our UFH. Generally only 1 is required to maintain the desired temperature in the 'off peak' window when the UFH is on. The idea was that if one failed we could turn the other one on for a seamless transition and keep the heat flowing. There was no way to isolate the Willis heater that was 'off' so I essentially had a mixer where half of the UFH return water would go through the 'on' Willis heater and be heated, the other half would go through the 'off' Willis heater and not be heated. When the two flows rejoined for another trip around the UFH coils the overall temperature would be reduced after this mixing. To counter this I fitted a couple of isolation valves so I could isolate the 'off' Willis heater and send all the return water through the 'on' Willis heater. The obvious problem with that solution is the risk of turning 'on' an isolated Willis heater (hopefully the built in over temperature protection would save the day!) My plan now is to plumb the Willis heaters in series. This would: Remove the mixing effect. Remove the need to isolate the 'off' Willis heater. Still allow system redundancy. Still allow 2 Willis heaters to be run at once if it got particularly cold and the sun buggered off for a protracted period. What are the flaws in that plan? @Onoff could you elaborate?

I'll start a new thread...

(thread drift) Would your new best mate travel to Salisbury? It's difficult finding a decent plumber. Come the warmer weather I want to re plumb my two Willis heaters from a parallel to a series layout, I was going to have a bash myself but if there's a good plumber nearby then that would be preferable.