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roxiemanson

Posts : 11
Join date : 2014-08-04

underfloor heater

Post by roxiemanson on Sat 16 Aug 2014, 2:41 pm

The underfloor heater in my 1995 dart has not been working for about 3 years. Have had a couple of handy men look at it. They did try changing the therma coupler but it didn't work. It is sparking up and lighting, but when I let the button go it cuts out.

Did mention it to Ian in Riva and he said parts are not available. Any suggestions, is it worth getting a gas appliance technician to look at it?

Thanks  
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: underfloor heater

Post by Tow Itch on Sun 17 Aug 2014, 12:19 am

roxiemanson wrote:The underfloor heater in my 1995 dart has not been working for about 3 years.  Have had a couple of handy men look at it.  They did try changing the therma coupler but it didn't work.  It is sparking up and lighting, but when I let the button go it cuts out.  

Did mention it to Ian in Riva and he said parts are not available.  Any suggestions, is it worth getting a gas appliance technician to look at it?

Thanks   

Hi I'm a big fan of the gas heater as I often camp without EHU. You may have read my piece on the gas heater. [You must be registered and logged in to see this link.]
I'm going to talk you through a few simple steps to check out what is happening with your heater. Now you may realise that to work on any gas parts of a gas appliance within your home is strictly verboten and you must use a Gas Safe registered engineer. What you might not realise is that they are licensed in specific sub areas; fires, cookers, central heating etc. Now I'm not sure if they are given carte blanche on all appliances when licensed to perform LPG work but you will find far fewer LPG licensed engineers than natural gas engineers. This matters little to you as you may legally work on portable gas appliances.


Why did these "handymen" try to replace the thermocouple? Did they test the old one? Have they tested the new one? Dissimilar metals in the thermocouple create a potential difference across the thermocouple. This should be in excess of 20mV.

How to check the operation of your thermocouple.

To be honest it's only because I was trying to fault find on a more complex control system for an LPG fire (why does an LPG sound better than a LPG when L is not a vowel?) that I bothered reading about the voltages produced by thermocouples. Previously I would just have substituted an new thermocouple as 99%+ of the time that is what is wrong.
Don't want to cause you to loose the will to live but using Youtube videos to tutor is difficult as there are always bits I disagree with. 1st video as he shows how to unscrew a thermocouple. (It is a THERMOCOUPLE not a bloody thermocoupler as he seems keen to call it, not even in the lexicon of our demented American cousins is it known as such) 2nd video as he states acceptable and unacceptable voltages and shows better how to connect the multimeters probe. 3rd video. Only watch first 1.15 minutes as they state what the other problem or worst case might be.



Only two videos the third didn't say what I thought it did. I thought it mentioned the worst case scenario where the magnetic valve had failed.
So what if you haven't got in excess of 20mV? The favourites are that the thermocouple and the pilot light have become poorly aligned. Then rust on the thermocouple might affect the heating of its core. Thirdly rust or detritus on or in the pilot light is deflecting the light or reducing it's size.
So align the thermocouple into the flame path.
De rust or replace the thermocouple.
Pilot light. I'm not sure on the end if it's just a tube end blow into and around (compressed air line) to clear the tube and clear any preceding airway. If there is any jet that can only be cleared with an air line or a nylon bristle. No poking with a wire.

A general blow round with an air line inside the heater is recommended to clear the air inlets. Others have suggested that a blow out through the supply pipe from the heater end might clear whatever gunk had found it's way into the open pipe at the front. Those these actions aren't to fix a pilot light that extinguishes.

Less likely. The fitter was a gorilla and has tightened the new thermocouple so tightly he has buggered it. Also try cleaning the inner face of the connection. See video 2 where he cleans the thermocouple end on his shirt.

If you have in excess of 20mV it's looking like it is the magnetic latch on the gas control valve. You might try removing it and seeing if you can find a replacement or it might be the time to gain professional help at this point. The importers of the Riviera Heaters no longer exist. I tried to have a look for them they were made in The Netherlands by Gimeg. I can't find any references to the heaters on [You must be registered and logged in to see this link.]    

If you can't fix it easily it might be simpler to fit a working second hand Riviera Heater these appear reasonably frequently from about £50.00 to £200.00.

roxiemanson

Posts : 11
Join date : 2014-08-04

Re: underfloor heater

Post by roxiemanson on Sun 17 Aug 2014, 8:21 pm

Thanks for getting back to me on the heater, sounds a bit technical for me, think I will get some sort of a technician to look at it, will let you know how I get on. Thanks for all your info, really finding the site very useful.
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: underfloor heater

Post by Tow Itch on Mon 18 Aug 2014, 9:38 pm

Please do read through things again. I desperately don't want to miss things out and so I tend to make most things sound technical. These really are bulletproof items where it's just cleaning the airways out with an airline or replacing the thermocouple in more than 99.9% of problems

roxiemanson

Posts : 11
Join date : 2014-08-04

Re: underfloor heater

Post by roxiemanson on Mon 18 Aug 2014, 10:33 pm

Did a lot of scratching my head and looking at the heater again today along with reading all the information sheets. Not too sure how to clear out the airways, but don't have a airline blower anyway. It's so frustrating, it lights up no problem but just won't stay lit. Did ring a gas technician today but he really didn't like the idea of looking at it, outside his remit. Just reading everything I can on it at the moment, hopefully something will stick or work!

roxiemanson

Posts : 11
Join date : 2014-08-04

Re: underfloor heater

Post by roxiemanson on Mon 18 Aug 2014, 11:26 pm

Did a bit more reading, now understand the purpose of the thermocouple and the magneto-valve! Now makes sense why the unit is initially lighting up but then cutting out. I will try and get hold of the device to measure the current in the thermocouple. If it does not have enough charge, could you recommend where I would get one or what sort of thermocouple would be suitable replacement, (ps I live in Ireland  Very Happy ), did you ever hear of anybody changing the magneto-valve?

Thanks
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: underfloor heater

Post by Tow Itch on Tue 19 Aug 2014, 9:04 pm

roxiemanson wrote:Did a bit more reading, now understand the purpose of the thermocouple and the magneto-valve!  Now makes sense why the unit is initially lighting up but then cutting out.  I will try and get hold of the device to measure the current in the thermocouple.  If it does not have enough charge, could you recommend where I would get one or what sort of thermocouple would be suitable replacement, (ps I live in Ireland  Very Happy ), did you ever hear of anybody changing the magneto-valve?

Thanks

Ah well all the responses we gave about buying and none of it was quite as relevant as we hoped because you live in Ireland. You are the third or fourth person to contact us from Ireland. Obviously Dandy ownership is not as rare as we thought.
Do feel free to get yourself listed [You must be registered and logged in to see this link.]

In this case also I may have given a bum steer because the use of bottled gas is so much greater in Ireland you're sure to have an LPG gas engineer somewhere close.
If you want to check over the thermocouple a cheap multimeter can be found for less than £10.00 [You must be registered and logged in to see this link.] and thankfully there are plenty on eBay and Amazon.
You want a universal thermocouple suitable for LPG look on this site it shows what's in a universal kit and explains what is different about LPG thermocouples. [You must be registered and logged in to see this link.]
I wouldn't buy there though I'd try to buy from a real shop because you should be able to get invaluable advice. If you take the current thermocouple in it will help. Specialist gas spares dealers would be best though most plumbers merchants should have a universal thermocouple and be able to help.

No I don't know anyone who has replaced the magnetic valve. I'd guess it comes all as a one with the control device. I think you would be looking for someone to substitute a similar control device.  
If you can find a suitable gas spares merchant try asking them do they know someone who is happy to fix odd (as in one off) appliances. Do [You must be registered and logged in to see this link.] have a branch near you? Thermocouples page 48. I know not if they are bad or good it was just an example of a suitable type of business trading in Ireland. Though they will sell them DO NOT go to B&Q! Unless they employ very different people in Ireland you already know more on the subject than 98% of B&Q staff and they won't know anything about recommending gas service people.

The cleaning out is nothing more scientific than blowing around with a blow off gun after unscrewing the nut with the mica glass in it. Though you do need an airline from a compressor.

It's ten years since I've been over to Ireland (for which I will be cursed when I do go) and maybe it's because I had lots of older relatives but I thought you lot still had neighbours and pubs. (Most people over here hardly say hello to each other) there must be someone who knows someone for who this isn't beyond them.

roxiemanson

Posts : 11
Join date : 2014-08-04

Re: underfloor heater

Post by roxiemanson on Wed 20 Aug 2014, 7:31 am

Well just to say I really have found all your information on the different Dandy models most relevant and useful.    Really appreciate all the help. Just realised at the weekend when I measured my Dandy that it is a Delta and not a Dart! Great surprise.

Thanks for all the links, will follow them up. Will try the airline through the peephole, that is when I get my hands on an airline.
I think it is very useful to know as much as possible about the heater before I get somebody else involved. But going to take my time and see if I can sort it myself, think it will take a Dandy owner to go the extra mile to explore all avenues on this one. It's amazing how I can talk about thermocouple with the best of them since I joined this forum.
Anyway I haven't  seen another Dandy anywhere on my travels in Ireland so if I do upgrade in the future I will be travelling to UK to purchase.
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Tow Itch
Dandy Expert

Posts : 3175
Join date : 2011-06-20
Location : Leigh Gtr Manchester

Re: underfloor heater

Post by Tow Itch on Wed 20 Aug 2014, 7:46 pm

Hopefully the info on Dandy models was useful. Still don't understand why if yours is from the mid 90's it didn't have the name of the model on the side? It might only be 10" but the Delta is a lot more spacious inside than a Dart.
I wouldn't have given a lot of the buying advice as a lot was not relevant to you.

Good for you at having a go at the heater yourself.
You only have 4 possibilities:
Defective thermocouple. 2nd one???
Poor electrical contact. Clean both surfaces
Poorly aligned thermocouple. Unfortunately I can't think how the thermocouple lies relative to the gas jet. Wouldn't know how to describe it if I did and would be dubious that you could take a photo through the nut. Does anyone have their Dandy up at the moment who could take a photo of the thermocouple's position and preferably the position relative to the pilot flame   Blast the only person I know with a [You must be registered and logged in to see this link.] is Phoenix and they don't have a gas heater. Couldn't find any of their intriguing "what is it" photo competitions taken with it.
Broken magnetic catch in the gas control valve.

I could be increasing the size of your tool kit exponentially. I'm not sure it would work and you would need at least a second pair of hands but you might be able to get one of these down the peep hole and ply it on the thermocouple to see if it then opens the gas tap [You must be registered and logged in to see this link.]
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Phoenix
Dandy Expert

Posts : 1435
Join date : 2011-09-07
Location : South Norfolk.

Re: underfloor heater

Post by Phoenix on Wed 20 Aug 2014, 11:39 pm

  We know   


Here is the [You must be registered and logged in to see this link.] to the boroscope you couldn't find Tow Itch.

Sorry we don't have a heater to take the pictures you need.

roxiemanson

Posts : 11
Join date : 2014-08-04

Re: underfloor heater

Post by roxiemanson on Thu 21 Aug 2014, 2:49 am

Ah really appreciate all your help, will let you know how I get on Smile 
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peridot
Dandy Admin

Posts : 545
Join date : 2012-09-01
Location : Newport

Re: underfloor heater

Post by peridot on Mon 25 Aug 2014, 12:22 am

I'll be away next weekend and, given how cold it's been at night recently, expect to be using the underfloor heater I fitted earlier this year for the first time in anger.

I'll try to either photograph or describe how the flame looks relative to the thermocouple.

I've just managed to repair my portable 3-way fridge that had a similar problem of not remaining lit (and not cooling properly when it was lit). That was down to blocked jets in the gas burner. It took a hell of a lot of dismantling to get at the relevant part, but just a quick rub with some fine emery paper and a blast of compressed air to get it back to full health.
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peridot
Dandy Admin

Posts : 545
Join date : 2012-09-01
Location : Newport

Re: underfloor heater

Post by peridot on Mon 01 Sep 2014, 10:48 pm

Well the weekend was not as cold as expected, but very windy and we were on a very exposed site which meant that I didn't get to complete my awning rail attachment as intended - but that's a story for another thread (and more importantly a good excuse for another weekend away in a week or two).

I did fire up the heater and managed to get a reasonable picture of how the thermocouple sits relative to the first flame slot in the burner. There's a bit of carbon on the tip of the thermocouple that you can see glowing brighter in the shot below (with viewing nut removed). There's only around 3mm of the thermocouple tip in the flame so if that first burner slot is slightly blocked at the gas inlet end it's likely to cause the heater to cut out.



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