Russdl

You make a convincing points Peter. At the stage when I was convinced it was absolutely the wrong pump I had planned to change it. The plumber who told me that it was the wrong pump also told me that the pump in the Willis circuit was a crap pump so I was going to replace the reported ‘crap’ pump the current Wilo and get a bronze Wilo for the hot return. Has the plumber sold me a dummy or is it a crap pump? (Water softener pipes in the way. I’ll get a better picture in a bit) I should add, he wasn’t trying to sell me a replacement pump.

@SeanCrowley It’s not a stupid question, the stupid question is the one you don’t ask. I’m guilty. We have done the same as you are planning. As already mentioned, water is easy. In our case we turned it off at the meter, and started digging a hole in the plot where we thought it must be running. We found it quickly enough - it was miniature, 3/8th” iirc - and got some adapters to connect it to some MDPE and set up a standpipe T’ed off to a shed with a toilet and sink in it. BT or whatever they are called now turned up relatively quickly to remove their cable but if they hadn’t I suspect a site accident could have removed it as effectively. Gas took a while, but was not a big problem, we’re not using it anymore so it was a simple disconnect. Shortly after ours was disconnected a house nearby was demolished and the whole house was raised to the ground save for a tiny bit of wall with the gas meter attached (I guess they got bored of waiting?) I was quite astonished to see that but they didn’t seem to generate any problems for themselves by doing that. Electrikery. If you can plan ahead well enough, unlike me, then you can request a service alteration and set up a temporary building supply. If you’ve planned well enough then you won’t need to move that temporary supply, just connect it up to your new house when the time is right.

Again, that shows what I know. I thought Wilo were the manufacture of that pump?

I called up, gave the tech guy the part No. (it seems they call it a Star No?) and asked if it was suitable for a hot return circuit. I reckon he was punching that part No. into his computer, and computer said 'no'. He told me I needed an SB60, as I explained exactly what it was for he said the much cheaper SB30 would be more than sufficient. I couldn't comment further on his competency or otherwise I wouldn't do that, I was the heretic after a standard light switch in a downstairs WC (not literally). I like change unless there is a good reason not to. I appreciate your explanation as to how things have evolved in the manufacturing process, had I had that information last night I either wouldn't have called Wilo this morning, or if I had I would have been much better informed. As I said and @PeterW highlighted, this is in potable water supply, so trying to minimise use of the inhibitors ?

Clearly indicating how little I know about these pumps. The impeller body is black plastic or some such thing. I understand what your saying but Wilo say it’s not the correct one. All the pumps on the Wilo website that are specifically for domestic hot water recirculating loop have a bronze impeller body. The tech guy told me I had the wrong one and I feel obliged to go with that advice.

@Onoff I’m afraid I have no clue and as information has become conflicting I’ve come down on the side of the Wilo tech guy. Like I said, this all started after three separate commentators told me it was the wrong pump. I wouldn’t have had any idea.

It’s not a plastic body. It’s cold and scratches just like any alloy would and there is definitely something ferrous inside (magnet sticks with ease). I’m minded to stick with the Wilo tech guy on this and not the eBay resellers. Maybe the Wilo guy is wrong but with this conflicting info I’ll stick with him. Regarding the hot return pipes. I’ve got that wrong. I’ve been reminded that the pipes are plastic coated copper and I agree the solution to turning it on and off is elegant.

Quick update. So the consensus on here and the www is 'bronze pump' for the hot return. I didn't want to speculate further so I called Wilo to get some answers. Wilo technical confirmed that it is the incorrect pump for a hot return circuit and that after time I would get rusty water from the taps and finally a pump failure. Why on earth would the very knowledgable and highly skilled plumber fit the incorrect pump to our hot return circuit? He must have known what he was doing? The list price of the incorrect fitted pump is £120. The list price for the correct pump is £548. (That £548 is the list price for a Wilo SB60, a Wilo SB30 would probably do what is required with ease and can be had for £162)

That would appear to be the consensus and makes sense to me. But do I actually want a corroding pump in my potable hot water return. I'm sure it's not going to kill me and probably not event kill the taps but for how many years would I be running rusty hot water in to the sink before the pump finally fails? Neither can I which seems odd. Is it likely to be a discontinued model? ~~~ Googling this issue led me to this separate concern. Can I use Hep2O in a continuously operated re-circulating system? No. Continuously operated re-circulating systems (Secondary Hot Water Circulation/Ring main installations) are very different from conventional hot water supply and central heating systems found in domestic properties, for which Hep2O products have been tested. Thats from the Wavin site, and Hep2O has been used in our hot return loop. As ours won't be continuously operating I think we're in the clear but it was going to be initially. I didn't really want a hot return circuit but the plumber cajoled me in to agreeing to one and came up with a simple solution to only make it run when the bathrooms are occupied.

@TerryE Wow. Thanks for that explanation. I’m going to have to read it again and again though before it sinks in!

On the subject of hot returns, 3 times now I’ve been told that the pumped fitted in out hot return loop is incorrect. The first to tell me was an electrician so I kinda ignored him, the next two were plumbers so I had to pay a bit more attention. They all say that the pump in the picture below is for a heating circuit and should not be used in a hot return circuit. They tell me I should have a bronze pump for the hot return. I know nothing of these things, can anyone shed any light on this?

Our set up has twin Willis heaters, and it was quite by chance that I realised one wasn’t working, and hadn’t worked since installation however with just one Willis heater working the UF heating worked perfectly. Probably a stupid question coming up: Looking at my energy consumption when the one heater was on, it was consuming a steady 3kW. It’s dialled down to a max of 35 degrees and the UFH thermostat was set to 22 degrees. Could I have get more heat into the slab if both were working but the thermostat stays at 22 degrees? It seems to me that one Willis heater was doing all that was needed to be done. If both were working where would all that extra energy go?

The reset button wasn’t the issue but I took the cover off to be sure.

sorry for the delay responding, work stopped play. Here are images of above and below.

@Onoff I’ll bow to your and the electricians superior knowledge, like I say, we’re not having conventional switches, they will either be outside the room or Quinetic. It’s just not what I wanted ‘tis all.

Knowing nothing about the subject but being convinced by John Wards explanation, and spending a good deal of my time in continental Europe where it is common place, (as are the plug sockets in bathrooms) is the reason why I asked for normal light switches. As I recall JW only referenced previous regs after explaining the current ones? Anyways, the answer was I wasn’t going to get standard light switches and I seem to recall a good explanation from the electrician as to why I couldn’t. No idea if the explanation came from Section 701 that you mention. So we won’t. Still don’t understand, but hey ho.

No clue. If that is what I need to do, and it is the case then there are certainly a couple of obvious locations for isolation valves. Green rings in image below, any reasons why I shouldn't get the replacement plumber to put a couple in?

I'd read the posts. I insisted. s'not my fault that I'm crap at Googling! Thanks Peter. Pretty sure it's not that but I'll recheck, as I said it wasn't the first 'Willis heater Rodeo' for the electrician who checked it.

Octopus do a 3 phase smart meter, well at least down these parts they do.

@joe90, I wish he was my electrician and we do know him fairly well from first fix days but sadly he was just 'passing through' and dealing with another, unconnected, issue we've had. I do have a multimeter and I reckon I can test it. Buggered if I can find the replacement I'd need though if I confirm that is the problem. Some thorough Googling has turned up nothing that cost less than the whole unit so far, but my Googling skills have always been less than proficient.

Good spot, it had been on for 3 days before I worked out it wasn't working. When it became obvious the LH one wasn't working, I left it off. That sounds even simple enough for me to do, thanks. As it happens we had an electrician in the house for a totally unrelated reason whilst I was away last week. The good lady asked him to take a look at the suspected defective Willis heater and he declared it dead, no mention of the thermostat specifically being dead just "it's dead". The electrician as it happens is well versed in Willis heater UFH having worked with the installer of our system in the past.

@joe90 That looks like it may be the thing, they look very similar but I wonder if it's worth the faff? Any idea how I check to see if that really is the bit that is screwed? Well outside of my skill set which is why I got a 'pro' in to do all that stuff in the first place...

Can you give me more clues? How would I do that?

We have aluclad 7016 on the outside, I wish we had gone darker with 9004. Inside its a pale timber. Looking at @PeterStarck pictures, I wish we had gone RAL9004 inside and out.

I really think this is the best way to heat a passive house (kudos to TerryE, I think he was the inventor?). My Willis heater UFH was recently commissioned and within a few days the trades were asking for the heat to be turned down. We have no controls for it so it was turned off. A week later, in freezing conditions it was still pleasantly warm inside. We do have a problem though as the left hand of the two Willis heaters doesn't work, and evidently from my energy usage it never has, so I guess it was never tested. Who would have thought. There is a peak in consumption as they were turned on on the 27th Jan but not enough of a peak to suggest that both heaters were working, probably just the RH Willis heater and the kettle. The following day it's just one Willis heater and the odd bit of kettle action. It's not the reset button on the bottom, so it needs to be replaced. I think I've found the exact model and as @TerryE pointed out, they are so cheap I may as well get a couple of spares. I guess it's going to be easy to replace. How do I go about replacing it without filling the whole system with air again - or is that inevitable? I also need to get some inhibitor in the system, should I do it when I replace the defective Willis heater or should I run the system for a few days to make sure all the air is out before I put the inhibitor in?