Help on faulty Ademco 2226 dry mounting press

[andy_parks]

Hello to everyone on this forum. This is my first time actually making an entry but I have read with interest previous entries, found it a very knowledgeable forum and have decided to join myself. This is partly because I am about to start my own picture framing business after working for 21 years for other picture framers! Also I like the idea of knowledge sharing which is what the Internet is all about, isn’t it?

Anyway, enough of that and onto my problem. About a year ago I bought a second hand Ademco 2226 dry mounting press. Absolute bargain at the time and knew it would come in very useful when the time came to start up on my own. It worked fine when I tested it at the seller’s location and the thermostat did its job and stopped heating the press at 85 degrees C. Because it has taken a year to start my business due to studying, the press has been stored in my shed which must have been slightly damp. When I took it to my new workshop, it blew the trip when I turned it on. Noticing a kink in the electrical supply wire and thus thinking that I probably broke the electrical wire in transit due to the press sitting on the wire to get it to my workshop on a trolley, I have now re-wired the mains supply lead. The friendly electrician assures me that I have bought thick enough cable for the current needed. Now when I turn on the press, it has mains supply with the red light glowing nicely. When I turn the thermostat on to activate the heating platen, the trip kicks out again. I wondered if anyone had any experience of this problem? Basically is it the heating element that has gone or the thermostat? I think thermostat. This is because a grill heating element once blew on my cooker but this only resulted in the grill not working but did not blow the trip and the rest of the cooker worked. This is the only piece of experience and hence logic I can apply to this situation. I understand that Conservation Resources sell the parts and I am going to get a quote for the various pieces I will need to make the press work again. Only thing is, which part do I buy? Should I flip a coin with heads for heating element or tails for thermostat?! I think testing it all with a suitable volt meter is a bit beyond me, unless you know different. Any advice that anyone could give me would be very much appreciated. Thanking you all in advance.

[osgood]

Andy,

Diagnosis of electrical faults via email or a picture framers forum is pretty well impossible!

I take it that you are not an electrician, so it's possible the fault could be in the way you wired the new cable in, or that the cable is incorrect. It's also possible that the thermostat or some other part on the press is faulty. It's also possible that the wiring in your premises cannot cope with the requirements of the press.

You mention a friendly electrician, why don't you pay this guy to test everything to see whether he can diagnose where the fault is. It seems to me that this should be your first option, rather than relying on a group of picture framers to diagnose the problem at long distance!

[John]

Sorry that your first post could not have yielded a simple solution to your problem Andy. But I must concur with Ormond's advice. The only glimmer of hope that I can give is that there is a remote chance that your problem might be caused by damp from the period of time in storage, but given the recent weather this is a real long shot.

Welcome to the forum, and good luck with your new venture.

[mick11]

Hi Andy,

Check the rating on the trip it may be to low, this is normally shown in amps.
There should be a plate on the press with electrical details. If it shows amps, your trip needs to be a higher value than that shown.
If it shows watts devide the figure by 240 to give you amps.
Also take into account anything else that may be protected by the same trip.

[Lemon_Drop]

Hi Andy,
I got a Ademco Hard Bed Press also, but im not sure about electrical stuff. I dont think Ademco makes them any more I think they were taken over a few years ago. I got and address of an old manual, its,
Ademco Drimount Ltd.
Coronation Road
Cressex Industrial Estate
High Wycombe
Bucks HP12 3TA England.
Phone (0494)448661
I was checking before about it and i think Dermot had a link about who took them over, the nearest thing i could find is http://www.drytac.com/hardpress.asp
Maybe they could help you out, at the moment its a 50/50 chance your going to pick the wrong part. It might be cheaper to get an electrician to check it out, if you use this forum for guidance about what part to buy everyone will just be guessing also, unless we have an expert on electrical parts here.

[Not your average framer]

Hi Andy,

I not only have an Ademco press like your own, but my original occupation was as an electronics design engineer, so I will try to help. First I need to ask a question and I will also give you some background information too:

Question - The trip which is tripping out, is it the normal power circuit excess current trip or is it a RCD trip, (Residual current detection) trip?

Background Information -

If it is tripping because your press is drawing excess current then there may be a wiring fault or a short circuit between live and neutral some where on the output side of the thermostat. If it is tripping due to residual current detection, then there is an imbalance between the current flowing in the live and neutral connections due to leakage or even in extreme cases a short from live to ground (earth).

My own Ademco originally came with a rubber insulated cable which deteriorated and caused similar problems to that which you describe. I then replaced this and everything worked just fine. However, the current rating of the cable is not the only consideration when selecting a suitable cable. The Ademco 2226 draws about 2,500 watts and even with an adequately rated cable, the voltage drop caused be the cable can result in less than the full available mains supply voltage being applied to the element. This can substantially increase the time required for the press to reach it's operating tempature. Therefore, I suggest that you keep the cable length to the minimum required and buy the highest rating cable you can to get the lowest voltage drop. Even an apparently small voltage drop (say 10 volts) can be significant as the power produced by the element is proportional to the square of the voltage applied.

Do not be tempted to replace any of the high temperature wiring within the platen enclosure without good reason. The wiring in there is almost indestructable, it has glass fibre insulation and withstands enormous temperatures. Also be very careful if you decide to undo the screws on the control panel to look at the thermostat wiring - on mine it is all connected with push on tags which may just pop off without it being obvious where there should go to and you need to understand how these thermostats work if you want to rewire them - there's a heating element inside the thermostat which must be connected to element side of the thermostat to reduce the difference between the on and off temperatures.

Finally a quick word of warning, the fairly simple circuit diagram in the users handbook does not truly show the full extent of all the wiring inside.

Tell me which type of trip is tripping and we'll take it from there. You may need access to a suitable test meter after this.
Cheers,
Mark

[andy_parks]

Hi everyone so far who has offered advice. Thank you very much for all your efforts to date on an obviously tricky problem.
Especially to Mark "not your average framer": That sounds excellent advice not to touch the wiring inside! Unfortunately, I have taken it apart but I have done this before with these presses (but not for this problem!). The wiring all looks fine. Can't see any tell tale scorch marks on heating element but you never can tell! I have looked at the trip thinking it might be too low a rating as well, but it is the main trip for the unit and it is rated at 63 amps, which I find hard to believe it is generating more than that! It is an industrial unit with plenty of other high use elecrtical equipment there so it should eventually work. I will look at the trip tomorrow and find out which of the two trips I have that you describe. I have also tracked down a supplier of bits for the press. They reckon they have both the thermostat and the heating element and I might be able to get them on SOR, which would be great. Wiring in a new thermostat shouldn't be a problem but you never know! Have made careful diagrams of what wire went where etc so feel pretty confident of replacing thermostat. Heating element looks a bit more tricky but I think I would be tempted to try the thermostat first as this may have got damp during the winter and stayed slightly damp once in my workshop when I went to turn it on. Hence that could be creating the trip out. Does that make sense or am I just trying to convince myself it is an easily fixable job?! Before I do anything though I will let you know what type of trip switch is installed. My brother has an elecrtical testing meter so may be able to test it all if needed. May have to bite the bullet on this and get a service engineer in but really want to save the money especially when just starting up in business! Anyway, will let you knwo the outcome and thanks again for your time.
Kindest Regards,
Andy Parks

[Not your average framer]

Andy,

As you probably have already seen, the heating element is a long thin circular section like a longer version of an electric kettle element. The centre conductor inside this is the actual heater wire (be careful it also can break if bent). This conductor probably if measured would show a resistance reading of about 24 ohms. If so your element is intact.

However, the insulation resistance between this conductor and the external sheath could be the cause of your problems. Normally I would expect this insulation resistance to be something like 100,000 ohms. Unfortunately, the insulation material inside the sheath is a mineral in powdered form and can absorb dampness which reduces the insulation resistance, possibly enough to trip an RCD trip. If this is the case, let me know and I will suggest how you can dry this out and solve the problem. I would recommend that you don't remove the element from the platen as this can sometimes damage the element.
Cheers,
Mark

[andy_parks]

Hi Mark,

Hmm, interesting. I thought the heating element was the huge part of square metal that snakes around the 22 x 26" plattern. The other part you mention that if I am right you are saying is the heating element is only about 12" long, copper and is the bit that is attached to the thermostat with a copper wire and is screwed down to the base plate in two places. This bit I think comes with a thermostat as it is wired straight in to the back of the thermostat. All very confusing and jolly good fun! I shall first of all look at the trip and also ask the land lord as he seems quite a knowledgeable / helpful bloke as well on the type of trip. Thanks again for all this invaluable info. Will be in touch soon. Thanks again everyone.
Kindest Regards,
Andy

[andy_parks]

Hi Mark,

Yes the main trip has RCD written on it but the other 4 in the box do not. It definitely is rated at 63amps. The other four must be for the three sets of double sockets and the lights but they do not have RCD on them. Does this help?

Thanking you very much in advance.

Kindest Regards,

Andy Parks.

[Not your average framer]

Hi Andy,

Yes, it does help. Can I assume it is the RCD trip which is tripping out and not any of the other lower current trips? If so it seems very likely that the fault is excess leakage current from live to earth caused by dampness within the mineral insulation around the element, which is circular in cross section and as you originally suspected is the bit which snakes around the surface of the platen.

The shorter circular item you described, connects via a thin copper tube called a capilary tube to the thermostat. This type of thermostat is known as a "simmerstat", they are still made and rarely if even need replacement unless damaged by human interferance. They are better known for their use in electrically heated tea-urns.

Is your electrician friend a proper electrician or someone who just knows a bit about it? There are two very good reason for me asking this:-

Firstly, we need an accurate measurement of the leakage resistance from live to earth to confirm what actually is causing the trouble.

Secondly, my suggested way of drying out the element is not something I would like to suggest without someone who knows what they are doing at your end who can make sure that it is done safely.
Cheers,
Mark

[andy_parks]

Hi Mark,

Thanks for that very detailed response. The electrician is fully qualified and works with my brother in the building trade so he should (?) know what he is doing. I am trying to arrange a visit down to my workshop with him but I expect I may get a standard "two weeks" type of quote as it is for "a friend of a friend" if you know what I mean! Any technical info on what he should be reading on his meters etc would be very much appreciated. Thanks again for all your help. Very much appreciated!

Kindest Regards,

Andy Parks

[Not your average framer]

O.K. Andy,

This is what I am thinking, what it means and what I am suggesting needs to be done.

If I am understanding this correctly the RCD is tripping out, but the other trips remain un-affected. As I would normally expect all the other trips to be connected through the RCD trip which has a higher rating when operating as a normal trip, but only the RCD trip is tripping out - It is logical that the trip is being tripped in it's RCD mode (Residual Current Detection). This means that some current is escaping from the live supply connection into the earth connection.

Before the days of RCD trips this would have gone undetected and you would have been able to use your heated press without knowing anything was different. Nothing would have tripped, the platen would heat-up and the dampness within the element would be driven of as steam without you knowing anything about it - End of problem!

So, why do we have RCD trips? Mainly because they save lives by tripping before the residual current escaping from an appliance or instillation can reach a sufficient level to cause death by heart failure. It is generally considered that 20 milliamps through the heart is about the lowest level likely to cause heart failure - so your RCD is probably designed to operate at that kind of level.

Unfortunately, the dampness in the insulation of your heating element appears to be sufficient to cause enough current leakage or residual current to operate the trip. However the solution to the problem is to heat-up the press and drive out the dampness, but without tripping the RCD. There is a way of doing this, but in this day and age where safety standards are high all we are all legally required to act accordingly, we have to do a risk assessment and be able to show that we can disconnect the earth and run the press without taking any risks or causing any danger whatsoever.

So this is how we do it.

1. We measure and record the leakage resistance to ground from both live and nuetral to earth. This is neccesary to prove that we are right about the leakage current and demonstrate the need to do something to correct the problem. Also when we measure this resistance later after heating up the press we need to be able to check that the problem has been corrected. Before and after readings will prove if we have gained any improvement or not.

2. The earth connection is there to protect life and to make sure that the metal frame and casing cannot become live. So unless we don't care or are completely nuts, we can't just disconnect the earth and not care that enough leakage current is flowing to the now no longer earthed case and frame to possibly kill someone. So this risk must be addressed and rememedied and we need to prove that it is still safe to use it for long enough to dry-out the dampness.

3. To do this, as a strictly temporary measure only, we disconnect the earth wire in the plug on the end of the mains supply lead and connect it to the neutral, but before we do this we make sure that this is only done under the strict supervision of your electrian and after he has also confirmed by testing that the voltage appearing at the neutral connection is at a safe and low level and that the earthing connection of the case and frame is a good, solid, reliable low resistance connection which will prevent any un-safe voltage from appearing on the case or frame.

THIS IS NOT SOMETHING YOU SHOULD BE EVEN THINKING OF DOING BY YOURSELF - GET THE ELECTRIAN TO DO IT - NOT YOU!

After the dampness has been driven out and the leakage resistance has been checked, the earth should be re-connected correctly as before and your electrian asked to verify the safety of the press for use. I suggest that you print this out and show it to the electrician for his agreement and leave the rest to him. I hope this helps.
Cheers,
Mark

[Framing Norah]

Andy

[Framing Norah]

ANDY!!

[Framing Norah]

ARE YOU STILL THERE, ANDY?

[andy_parks]

Hi everyone,

Well what can I say but thank you all very much. Absolutely excellent advice and so glad I joined. I have a bundle of print outs now from all your info to date for the electrician to use when he comes to have a look at the press. Lets hope it works soon......! I will let you all know how I get on with it. Thanks again for all the entries.
Kindest Regards,
Andy