Janus, Eljan, Hijan and Intejan hot water circulators

Most Johnson and Starley warm air heaters are available in versions which also heat a hot water tank. This is done by factory-fitting a second, very small gas appliance inside the cabinet of the warm air heater, called a “hot water circulator”. There are four models of circulator named Janus, Hijan, Eljan and Intejan. They are all very similar but with detail differences and they all share the gas supply and flue of the parent warm air appliance.

The Janus is the most basic, with a permanent pilot flame, mechanical thermostatic temperature control and time control. It has no external electrical controls so runs 24/7/365. There is a loop of finned pipe inside a small combustion box with a gas burner underneath, and a flue collection hood above. The gas flame size beneath is continuously and automatically to suit the amount of hot water demand from the household. The flue hood collects the burned gas fumes and connects directly into the main flue from the warm air heater within the appliance case, so the installer still only has one flue outlet to connect to the chimney. Circulation of heated water from the circulator to the hot water cylinder is by natural convection, which means there is no pump and the hot water cylinder needs to be installed several feet higher than the circulator, usually in an airing cupboard directly above the warm air heater downstairs. A very simple appliance, usually fitted in the earliest models of J&S warm air heaters from the 1970s and 1980s.

The Hijan is broadly the same as the Janus but with the addition of an electrically operated on/off gas valve, which means the hot water can be controlled and turned ON and OFF by a time switch, rather than being left on 24/7, and an “oxy-pilot”. The oxy pilot is a more sophisticated design of pilot burner that is sensitive to the oxygen concentration in the air and turns the appliance OFF if the oxygen level in the room atmosphere begins to deplete, which is a leading indicator of the type of fault which later leads to carbon monoxide gas being produced. An additional safety device.

The Intejan is a fully automatic, room-sealed circulator with electrical time control, electronic ignition (so no permanent pilot flame) and electrically operated thermostatic control. The Intejan is fitted inside the Economaire room-sealed range of warm air heaters.

The Janus, Hijan and Intejan between then are a whole lot more troublesome than any of the warm air heaters they are fitted within. Here are the main issues they suffer from:

Common faults and fixes:

1) Soot contamination of the heat exchanger. 

Flames lick out in the most alarming way from around the bottom of the water heater, on the right hand side, inside the main hot air boiler.

The heat exchanger is very simple, just a loop of pipe covered in fins. Nothing to go wrong with that, you would think, from looking at one. The trouble is, it is also fantastically good at trapping any fragments of soot produced by the continuously-burning pilot flame should it not remain scrupulously clean and regularly serviced. For years, the pilot flame can burn perfectly well with a nice clean blue flame but as years pass, fragments of dust in the pilot burner assembly begin to accumulate and the flame begins to burn with a yellow tip, this is bad, REALLY BAD because a flame burning yellow is producing fragments of soot, some of which get trapped in the fins on the heat exchanger. Eventually if this apparently trivial soot production is not caught and remedied in the next annual service, the blockage ceases to be trivial and the restricted flow through the heat exchanger begins to affect quality of combustion of the main burner flame too, and the process then runs away and as lots of soot are produced the heat exchanger fully blocks and flames lick out from underneath the combustion box instead of staying inside and the fumes going through the heat exchanger and up the flue/chimney. This is very dangerous as firstly the flames licking out are full of carbon monoxide (the poisonous one) and secondly, they tend to melt or burn any plastic nearby, in particular on the gas valve and any wiring insulation. 

Even regular servicing is no guarantee this fault will not occur as the pilot flame quality can degrade at any time, but servicing annually certainly reduces the likelihood as the pilot burner assembly should be thoroughly cleaned during the service. Provided however, the servicing technician realises how important it is to clean the pilot - it is small and easily overlooked. 

Fixing this fault once it occurs is expensive because it is so time-consuming. Johnson and Starley will advise draining the water system, removing the heat exchanger and thoroughly cleaning it. Getting every fragment of soot out is near impossible though in my experience, and once a heat exchanger has ‘sooted up’ once, it seems prone to doing it again. If I clean a sooted heat exchanger and put it back, it seems to soot up again in a few months or couple of years, so nowadays I fit a brand new heat exchanger and provided there is regular annual servicing, the problem seems never to return. (The labour charge to remove and fit a new heat exchanger being a little lower as I don’t have to spend an hour cleaning up the old one.)

2) Thermostat failure:

The water from the hot taps is too hot despite turning down the temperature control to minimum. The temperature control is on the front of the gas control valve, because the thermostat and gas valve are a single integrated part. So if the gas flames continue burning (often on low/minimum flame) when the water is plenty hot enough, the thermostat is failing and a new gas valve/thermostat assembly is needed. A straightforward repair if rather expensive in parts. 

3) Pilot light has gone out.

On all permanent pilot light appliances the pilot flame occasionally extinguishes for no obvious reason, and while 40 years ago most gas boilers had pilot flames that people know how to re-light, nowadays many don’t and are perplexed about how to do it. Firstly, here is a photo showing what the pilot flame looks like in a  Janus water heater, and where it should be. If yours does not have the flame in this this photo, your pilot light needs re-lighting. 

To re-light the pilot flame, ideally you’ll need a long-reach kitchen gas lighter such as this one made by Clipper” to actually light the flame. Sometimes there will be a piezo electric button fitted to send a spark to light the flame but these often do not work and cannot be relied upon. Even if they send a spark, the spark may not contain enough energy toi actually ignite the gas but a Clipper style gas igniter like this will always light the gas flame, provided there is actually gas present.

So to actually light the pilot flame, firmly press and hold in the right-hand button on the gas valve with the red ‘spark’ symbol. This starts the gas flowing, then click the long lighter to light it and insert the end in towards the position of pilot flame. The pilot flame itself should immediately ignite and start burning. Keep holding the “spark” button in for approx 20-30 seconds to allow the heat sensor (thermocouple) to warm up, then let go of the button. The pilot flame should remain alight and the appliance should now work and supply hot water. 

The temperature of the hot water is regulated by rotating the larger black control knob above the two buttons. Anti-clockwise makes the water hotter. Fully clockwise turns the hot water OFF, but leaves the pilot flame running. To turn the pilot flame off, press the left hand button with the white spot. 

Finally, most warm air boilers have instructions similar to the above printed on a label somewhere, but not all! 

4) Pilot flame will not re-light

If re-lighting the pilot light doesn’t work and it keeps going out on release of the button, or won’t light in the first place, blocking of the air port on the pilot flame burner is usually the reason and you will need to call a gas technician to dismantle and clean it. This mainly happens on the Janus model with the basic pilot assembly. The symptoms are the pilot flame going out and refusing to stay alight when re-lighting. This can seem for all the world like thermocouple failure, but the thermocouples are almost bomb-proof on these and last for ever. What actually happens is the flame size reduces a little and doesn’t quite reach the thermocouple tip so it doesn’t heat up correctly. Cleaning accumulated fluff and dust from the air port restores flame size and it now stays alight. On the rare occasion the thermocouple genuinely has failed, a whole new pilot assembly is needed on the Interjan and Hijan models as their oxy-pilot is an integrated design with the thermocouple non-replaceable. On the up side, a hot water failure from this fault will have probably prevented a sooted up heat exchanger, as described above in 1).

5) Pilot flame burning yellow rather than blue:

If your pilot flame is yellow like a candle flame rather than nice pleasing steady mid-blue colour, then this needs fixing. The water heater may well still be working perfectly well but the yellow pilot flame will be producing soot, which will be slowly building up on the heat exchanger, and as it progressively blocks, main burner flames will start to lick out from around the gas control valve. The yellow flame is caused by the tiny air hole supplying combustion air to the pilot flame gas getting blocked with dust or fluff. It needs cleaning out and should be done as part of the annual service but often gets missed. Blowing it out with a length of flexible rubber tube fixes the problem and returns the pilot flame to steady blue. I’ll add some photos shortly of a blocked pilot burner air hole. 

If your Janus, Hijan, Eljan or Interjan water heater needs repairing and you are within driving distance of me in west Berkshire, call or text me on 07866 766364.

Mike

The pilot flame on a Janus 3 water heater. This flame should remain alight all the time. If it goes out, your hot water will stop working

“Clipper” long reach gas igniter, sold in most suoer-markets, or on Amazon or eBay

The whole gas control valve on a Janus 3 - showing the button with the spark symbol for re-lighting the pilot flame, and the ‘Off” button with the white dot. Also the temperature control dial. Rotate it anti-clockwise to raise the water temperature

Pilot assembly removed from boiler, showing the tiny air hole (port), blocked with fluff. I’m pointing at the hole with my pen. Fluff causes the flame to burn yellow and blow out easily

Here is the same pilot assembly, after blowing out and clearing the dust and fluff from the air hole. The flame will now burn steadily and solid blue in colour