The Big One radiator

[andyv1]

I have a Big One radiator as seen here. It was installed maybe 15 years ago, and I've asked for info from the main supplier in UK and also Raganradiatori who I believe to be the manufacturer in Italy. Nothing so far.

My problem is that only the central column gets hot, the others hardly at all, and it constantly clicks when in use. The installer had never seen one before and didn't seem to understand how to connect it up, so it may just be back to front. There are three separate colums and a connecting bar bolted on top and bottom. I've determined that the hot water comes in from the right and goes through a TRV, into the radiator then out the left hand side. This has a lock valve which seems identical to the internals of the TRV, i.e. a push down piston, but this is fixed in position by the cover cap.

Can anybody advise on this problem?

I'm hoping to solve this above ground. Going underground would entail pulling up an oak strip wood floor to get to the conventional chipboard flooring underneath.

 

[Madrab]

Has it always been like this or has it worked fine before.

 

[andyv1]

I don't think it's ever worked properly.

 

[Madrab]

That's going to be a difficult one if you don't have the manual/details around it. One test would be if you turn all the other radiators off and just have that one on, does it get fully hot?
Are those columns full of water too? If so, that'll be a huge capacity to have the water circulating properly. That being the case the radiator may be baffled to ensure the water circulates properly, i.e. it forces the water up to to the top of the radiator first but they are usually marked which is the inlet and which is the outlet. I would hazard a guess that may be the issue. Did the radiator come in parts or as one piece?

 

[Gasguru]

Pull it off the wall, remove the fittings and see how it's supposed to work. Either baffles are missing/blocked or the drillings into the coloumns are blocked...or the design is flawed and it will never work.

 

[andyv1]

Many thanks. As is usual I ask a question then find stuff that had never come to light before. I'm attaching a data sheet I've found. In this it looks like my set up is as per 320 in the bottom right of the page. It says I should have a diaphragm fitted, but I don't know where this would go or whether there is one. I somehow imagine it's meant to work by water coming in bottom right, going up one side to the top of the first column then back down the other then along to columns two and three. The columns are hollow with fins inside so I assume the water runs within the outer walls.

I agree I need to take it off the wall and examine it.

 

[Madrab]

If yours is the same as in that manual and yours is piped so it flows in to the right then it is as per the MI. I couldn't see anything in that doc that mentions a diaphragm? It also looks as if there are multiple piping configurations which would question whether a baffle is needed, especially if each column has internal baffles, as it looks like in the diagram .

TBH I would shut down all your other rads and test this one on it's own and see what it does before taking it off the wall.

 

[andyv1]

You need to zoom in but on the bottom right there are various connection configurations which have an asterisk on - 120, 320, 430. Above this it says *By mounting the diaphragm. There's no mention elsewhere of the diaphragm on this document though.

I will shut all the others down first and see what happens.

 

[Madrab]

Ah yep got it now, didn't see it that as astrix on the 1st pass.

Yes, as it has a 'diaphragm' marked in the centre of the rad, I'd presume that's what we would call a baffle, it diverts the flow up the first column and then it cascades back down the other 2 to the outlet. If your installer didn't fit this then that's your problem. You would have to have it off the wall and take the tail out and see if you can spot the baffle inside the rad.

 

[andyv1]

Ah yep got it now, didn't see it that as astrix on the 1st pass.

Yes, as it has a 'diaphragm' marked in the centre of the rad, I'd presume that's what we would call a baffle, it diverts the flow up the first column and then it cascades back down the other 2 to the outlet. If your installer didn't fit this then that's your problem. You would have to have it off the wall and take the tail out and see if you can spot the baffle inside the rad.

Great thanks. So I turned off all the other rads in the house and got only the Big One going. I got an IR thermometer on it and it shows the central column heating up to 44 degrees but it's pretty much the same all the way up. The other two are 33 to 36 degrees. It seems any heat is rising just by conduction from the bottom bar but there's no actual movement through the columns. The water does comes out of the bleed valve at the top.

Next it needs to come off to see what's happening inside.

 

[Madrab]

It needs to flow in one way, from inlet to outlet. For it to work correctly it has to flow up the first column and then back down the other 2 to allow it to heat properly. The manual isn't the clearest though as it doesn't really identify how or where the baffle would be installed in a three column rad. Given it is 3 column then it would make more sense for it to flow up the 1st and back down the 2nd/3rd but given the middle one is the hottest suggests the baffle isn't correctly placed.

 

[Terrywookfit]

Do you have a 2pipe system ?

 

[andyv1]

It needs to flow in one way, from inlet to outlet. For it to work correctly it has to flow up the first column and then back down the other 2 to allow it to heat properly. The manual isn't the clearest though as it doesn't really identify how or where the baffle would be installed in a three column rad. Given it is 3 column then it would make more sense for it to flow up the 1st and back down the 2nd/3rd but given the middle one is the hottest suggests the baffle isn't correctly placed.

You're right - I've no idea where this diaphragm/baffle fits, but I'd expect it has to go in the bottom connecting bar between columns 2 and 3.

Do you have a 2pipe system ?

Not sure what this means, but it's a conventional pumped central heating system. I've got a gravity fed condensing boiler with header tanks, and a total of 13 radiators. All the others are quite normal - it's just this fancy one that's not right.

One consideration is whether the pump is up to it. It's a Grundfoss UPS 15-50 130 at the highest setting. It's probably 30-40 years old and may be getting tired.

 

[Gasguru]

Radiators can be piped up in 1 of 3 ways (and sometimes a mixture). 99% of domestic properties are piped as 2 pipe which is generally fine.
With all the other radiators shut down you have proven there's an issue with the big one.

 

[Madrab]

You're right - I've no idea where this diaphragm/baffle fits, but I'd expect it has to go in the bottom connecting bar between columns 2 and 3

Nope, it would fit between column 1 & 2 so it directs the flow up column 1, then would flow down column 2 & 3 and out the other valve. The fact that column 2 is the hottest, proves the baffle hasn't been fitted or has moved.

As @Gasguru mentions, you've now proven that the rad is at fault and would either need fixed, if you have/can get the baffle and fit it or replace the rad.