Junkers instant gas hot water

[Jose R Iglesias]

We are having problems with our old Junkers. Intermittantly it will cut out and stop heating the water. The flame comes up well when the hot tap is turned on but hot water no longer comes out. After some experimentation I found that there appears to be no circulation of water through the element(inlet and outlet pipes) However, if I turn the tap hard on in the laundry sink the normal flame comes on a little harder and heats the water find which leads me to believe that the system only needs a teak to ensure the water is circulated properly under normal tap pressure available elsewhere in the house. We have only just moved in but there was no mention of hotwater problems with the previous occupants, so I can only assume this is a recent problem.

[SelgasParticipant]

I am a little confused with your post does water always actually pass through the heater when a tap is turned on regardless of how far the tap is opened? If so and the heater does not light up then it is time the unit was fully serviced and new diaphrams fitted. If the water flow actually stops and does not run out of a tap when the tap is turned on then firstly check that the inlet water filter is clear and not blocked up which would also slow the flow of water down into the unit. More than likely a full service by an authorised service person would resolve your problem forthwith.

[tiggr2774Participant]

thanks for the reply,

The gas lights up just fine when a hot tap is turned on, but only cold water come out the tap. I can feel the outlet pipe of the heater remains cold depite the gas being burnt. This seems to be an intermittant thing depending on which tap we turn on. I have experimented with the laundry tap, which is convieniently close, and found when I turn the hot tap fully on the gas turns up another notch and the outlet pipe(and tap output) begin to heat up with water flow through the element.

Is there some sort of pressure related valve that might be sticking?

[SelgasParticipant]

Sounds like from your description that either of two things are likely to be the cause one being it needs a new set of gaskets and a water diaphram and the other if it is a thermostat controlled model the thermostat may be faulty – hire a service person to service it for you and things should return to normal quickly.

[daslerParticipant]

Reading this post I have a very similar problem. I have also got a very old Junkers instant heater which has been fine since we moved in (18 months ago). Yesterday, the hot water suddenly cut out and upon investigation everything appeared normal (pilot light still lit and flame heating the pipes). I rang a plumber to fix the problem but after 1 hour (and $180) of testing the pipes ect. he merely recommended contract him to replace the unit. His only explanation was that the controller that limits the flame level must have broken somehow, meaning the flame no longer had sufficient power to heat the water. As a student I immediately baulked at his range of ($2000-4000) to install a new unit. Is there any other avenue I could exhaust, is repair possible (worthwhile financially?), and is his quoted price for a new unit fair?

[SelgasParticipant]

Firstly lets go from the end of your question to the front cost to change over if it is an external model would be in the vacinity of $1500 or so as it is a simple task. If however, your unit is an internal one then depending on the flue presently fitted and a couple of other issues this could end up costing upwards of $2500 – depends on too many variables that we have not been able to view.

If your water heater is a thermostatic model then I would suggest that the thermostat file be checked firstly and if it has failed a replacement would overcome your current problem, if it tests to be sound then a full service of both the gas and water valve assemblies would have the same result.

[daslerParticipant]

I dont think it is a thermostatic model, and the plumber certainly did not check this. The quote I got today was $2200 for the Bosch 10/13 fully installed. On doing a little of my own research with other plumbers the best price I could get was $1150 for the Rinnai 26 without labour costs. Which looks like the better option, considering it would be about a half day job to fit it inside. Which would you advise as the better model/option. How much would a full service cost me?

[SelgasParticipant]

Firstly you are not comparing apples with apples – the Rinnai Infinity is an electronic instantaneous which is computer controlled to maintain temperatures when water is flowing and automatically adjusts gas flow to suit, it also requires power to be available 24/7 – no power no hot water. The Bosch unit ( new ones ) are available in the Hydropower range which do not require power supplies to operate and are more economical to purchase.

Bosch also make electronic units such as the E26 which apart from some very minor changes/improvements they are for all intensive purposes the same as a Rinnai so perhaps you should shop around for a price of one these units.

A full service to the unit you have there now including diaphram kits etc would probably set you back around $300 – $400.Selgas2007-10-31 13:24:38

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