Problems with Condensation ?

Just recently, we have seen a number of microwaves come into the shop with problems caused by condensation so I thought I would post some information.

A certain a mount of heat is generated by the components in making microwave ovens. By design, a microwave oven draws in cool air (normally into the vent at the rear), it blows that air over the components to cool them and then blows that same air through the oven cavity to carry away heat (and smells) and condensation produced by the food heating up inside. This has a couple of effects. One is that if the oven successfully carries the condensation away and out of the oven ( The door doesn’t need to be airtight to stop microwaves escaping – but that’s another post !), that condensation needs to go somewhere and like our Panasonic at home we often end up with a small puddle on the worktop in front of the oven after we have cooked something containing lots of moisture (rice or jacket potatoes for instance). This isn’t a problem now you know but customers are often alarmed, thinking that if moisture escapes then the microwaves also are escaping. The second effect is that if this happens often, then the interior of the oven will eventually become damaged, if the interior of the oven is painted white the paint may lift and eventually rust. Nether of these are dangerous but in the long term will look unsightly and ultimately shorten the life of the oven.

peeling microwave cavity

peeling microwave cavity

To overcome this problem, the easiest solution is to avoid the build up of condensation. Does the food that you are cooking really need to be cooked on that power level for that long ? Cleaning the oven afterwards will definitely help. Just a wipe around with a cloth after using the oven will take away the worst and if you leave the oven door open just while you serve up will give it long enough to dry out in most cases.

If, like this picture the damage has already been done. It wont be dangerous at this point but wont look very nice. This might be a good time to touch up the paintwork to restore the white finish. In this case it may not be a very long term solution as the roller ring will inevitably antagonize the paint but it will prolong the life for sure. We sell a touch up paint kit which contains everything you need to repair a white cavity such as this.

About microwaveexpert

The Microwave Service Company is based in Sellindge, Kent and provides repairs to Domestic and Commercial Microwave Ovens including 24 volt Samsung Roadmate microwaves.
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17 Responses to Problems with Condensation ?

  1. Stephanie says:

    This is not the problem. Moisture building up when nothing is inside the oven. Will this cause a problem?

  2. Neil campbell says:

    I’ve bought two microwaves the first I put back due to a lot of condensation developing the same thing with the second microwave which was a different product unfortunately I lost the receipt and had to keep it the older models seemed to get rid of the moisture but the new one’s are soaking wet inside with everything cooked at the right temperature time the two microwaves bought were well known brands

  3. Lou Harraway says:

    My microwave is the same, every one ive ever had has gone rusty. I leave the door open after cooking.i always clean it after use but it didn’t stop it going rusty. I have had microwaves in the £100 bracket and also in the £30 bracket but all do the same.

  4. Syax says:

    Bought a Sharp 800w and have the same issue. Feels like i have opened the bonnet of a broken down Beetle and all the inside is saturated. This wasnt an issue with microwaves before, so there has obviously been some kind of common design flaw across the industry in regards to venting. Having to mop the whole microwave after every use is not practical.

    • I think that there is a combination of microwaves being built more to a (lower) budget which results in maybe less efficient cooling fans and vents and being higher power so therefore creating more heat internally in producing higher microwave power. Certainly most microwaves seem to run hotter now. This heat has to be dissipated somehow and should be carried out of the doorway of the oven at least. Condensation on our at home does seem to occur more when the kitchen is cooler.

      • hilda says:

        If any consolation my M’wave (a basic but ‘quality’ Sharp) is at least 25 yrs old and looks/works like new but is only 600 watts. I now have been trying delivery of frozen ready-cooked meals which are for temps of 700/800 or 900 m’waves. All of these meals leave beads and pools of water after cooking, despite the fact that I have tried varying the cooking times above and below those recommended, so not just a problem of newer microwaves. I, too, never had this problem with frozen foods in the past and take badly with the daily ‘mop-up’

    • Lynnie says:

      That’s exactly what I have found! Never had any problems with the old model.

      Very annoying to have to keep drying it after every use.

  5. Lesley Dickinson says:

    My Russell Hobbs microwave has had excessive condensation since I bought it earlier this year. It’s a complete pain having to dry it out every time whilst watching the food get cold. Have thought about returning it but didn’t think I’d get any satisfaction.

  6. June Smith says:

    Mine is the same. Everything gets dripped on when I open the door. I feel that the vent isn’t doing the job it’s meant to do! Never feels very hot there, like nothing is coming through it.

  7. Alvin Phagoo says:

    I installed a GE cafe overrange and expecting the marching range next week. I have been having a lot of issues with condensation, especially when I use the fume hood. I replaced my old unit for a new one……I’ve never had any issues with the old one.
    I was expecting a the cafe line to be better!!!!

  8. Jeanne says:

    I have had my microwave since 2000 and it is only in the last year that there is all that moisture when I bake a potato. It has a rust spot already. I did’;t realize what was happening until I saw the rust. Now I leave it open like was suggested

  9. Cindi says:

    I just replaces a microwave that worked fine for 30 years. Now the replacement, purchased on 7/28/2017, a Mainstays Model MED2701, a 700 watt, 0.7 cu.ft. Microwave Oven is having a condensation problem with a brand new microwave. The condensation is occurring between the door and the protective coating on the inside of the door. I have never encountered this before so what I need to know is if this is normal or if it an indication of a defect The condensation does not clear. From between the layers of the door. In all of my years working with a microwave I have never encountered this before. If the condensation were within the main body of the microwave that would be a different matter entirely.

    Should I just return it?

    • Microwave ovens are built differently nowadays to reduce manufacturing costs. The doors used to be well built solid, airtight units but now are a lot more flimsy. They still do the job and stop microwaves leaking but do tend to let air and moisture between the layers. We contacted Panasonic about this and they assured us that as long as the condensation cleared eventually after use that the oven will be ok. Their only concern was that if the condensation didn’t clear then it would rust after a long time. if your condensation is clearing then it will be ok. i suspect a replacement of the same make and model will behave exactly the same. it may be worth thinking about what you are cooking and for how long also. if there is a lot of condensation it may be that you should consider reducing the power level or cook time as condensation will only be produced once moisture has boiled.

  10. Carol Kemp says:

    I’m a qualified demonstrator for ovens and kitchen appliances, I demonstrate how ovens cook by giving cookery demonstrations. Now retired but still interested. First used a microwave in 1982, attended a course on cooking with microwaves for my work. Today’s microwaves are unreliable and not fit for purpose if they have condensation! Water in the microwave reduced the heat needed to cook with. Water gets microwaved so taking some of the heat away from the food being cooked.

    Some food needs cooking at a high temperature for safety reasons. If there are cooking instructions they should be followed to ensure the food is cooked through adequately! A microwave should cook at the temperature of the setting used or there could well be health risks.

    Recall the microwaves that have excessive condensation they are not working as stated by the manufacturer – 800W is working below 800W. No one should be expected to use a cooking appliance that is substandard and a serious risk to health!

    • Condensation is created when water boils, turns to steam and then condenses as it cools. If there is condensation in the oven then it has boiled already and should be turned off. Steam is a sign that the water has reached its optimum temperature, it cant get any hotter than boiling, so switch the oven off at that point. If you feel you need to continue cooking reduce the power level so that the food is simmering, then at least you will not be generating lots of steam.

  11. Hope says:

    We have replaced 1 microwave already bc of mold arpound the microwave and cabinets. The microwave eventually went out. Now our new one has mold around it and in the inside with water in the bottom. It has a vent that runs to the roof

    • Most microwaves are designed to draw in enough air to cool itself and blow condensation during cooking but are designed to sit on the worktop where this is easy to achieve. it sounds like it doesn’t have enough power to blow out of the cupboard too. All you can do is wipe the oven around after use to clear that condensation. It may be worth considering that steam and condensation are usually only produced when water boils so maybe switch the oven off sooner to prevent the moisture forming in the first place.

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