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Review: Microheat HotShot

Discussion in 'Gen 2 Prius Main Forum' started by ttabbal, Dec 7, 2006.

  1. ttabbal

    ttabbal New Member

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    What is it?

    It's a little heating unit that installs in the washer fluid line to heat the fluid up before you use it. The idea is that it can melt frost, snow, and ice off of the windshield so you don't have to scrape it off by hand. I would recommend at least brushing the larger amounts of snow off first to speed up the process and protect your wiper system. It's not really meant to push large amounts of snow around. Heated fluid is also claimed to clean better, even in summer months. I guess I can comment on that in a few months. :)

    Installation:

    Finding room to mount something in the engine compartment of a Prius is a daunting task. This was probably the hardest part of the install. I ended up locating it on the front crossmember on the right side. Over by the washer fluid container. I was unable to use the lower mounting holes on the bracket, however the instructions that come with it say that it's OK to mount it that way. I had to remove the plastic trim panel that goes across the front of the car and the air intake duct that is right near the washer fluid container. I then mounted the unit just to the side of the radiator, about the only spot it would fit given the restrictions in the manual, basically that it must be within 30 degrees of vertical.

    Once mounted, you need to connect it inline between the washer pump and the nozzles on the hood. That's pretty easy as you're right there anyway. So I removed the hose from the pump for the front (I pulled the electrical connector for one of them and tried to use the washer to figure out which one I needed to use). The unit comes with hose and connectors so you have everything you need to splice into the system. I just pulled the hose off the pump and used a splice connector to the supplied hose. This way, I can revert to a stock setup with very little work.

    The only part left is electrical. The ground was easy, there is an existing engine ground right next to that area that I just added my wire to. The +12V was a little harder. The post is easy enough to get to, but this is 8AWG wire, quite thick for that area. I was able to remove the wire from the fuse holder with a small allen wrench and feed the bare wire through the little path the existing + wire runs through. Then cut to size and re-attached it to the inline fuse holder. The connector on the end seemed to work alright, but it's a tight fit. Everything goes back together, so it's not a big deal.

    Now you just have to get the control wires into the cabin. I used the big grommet in the firewall behind the inverter. It's another tight fit, but it can be done. I used a wire hanger to get through from the inside of the car, then used that to get a pull string into the hole. I used that string to pull the wires into the cabin and routed them up to the switch blanks. I only needed to remove the left side vent cover to get the job done. I then popped out the right most switch cover and used a dremel to remove about half of the lower holding tab and made a little slot for the wires to come through. Then I mounted the switch to the slot cover and all was well. Until the double-sided tape they gave me decided not to stick to the Prius dash material. I had some dashboard velcro in the garage that worked though, so now the button looks almost stock.

    First Thoughts:

    I've had it installed for a couple weeks now. There hasn't been a lot of snow, so I haven't been able to test it as much as I would like. However, it does seem to work quite well the times I have used it. The hot fluid cuts right through snow buildup on the nozzles and is able to de-ice the windshield. It also helps to melt snow and ice buildup on the wiper arms to keep them moving freely. The automatic mode works great when parked to remove ice and help de-fog the windshield on those cold mornings, and the standby mode keeps the fluid nice and hot. I think it's worth the price I paid for it, though I'm not sure if I would pay some of the prices I've seen online for it. I got it for about $70 from an EBay seller. I like the system, but the tight spaces in the Prius make for a harder install than other vehicles would have.

    I can take some pictures of the final product if anyone is interested.
     
  2. eagle33199

    eagle33199 Platinum Member

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    I'd be interested to know how hot the liquid gets. drastic temperature changes can be bad (i've heard stories of cracked and shattered windshields when someone throws a bucket of hot water on it to clear off the ice, but never actually seen it done).

    Pictures would also be great!
     
  3. seasalsa

    seasalsa Active Member

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    HMMM, I thought hot water freezes faster than cold?
     
  4. ttabbal

    ttabbal New Member

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    I'll try to get some pics of the install. Microheat claims they have it set up in such a way that the temp changes aren't harmful. It feels warm to the touch, but doesn't burn my hand when I put it in the spray. I haven't had any problems with it messing up my windshield in single digit temps. The Microheat website says they are installing it as OEM on some new GM vehicles and haven't had a problem. I also haven't heard of any problems researching it on the internet, though there were not that many people talking about it at all.

    I have not had any problems with the spray freezing, so I can't comment on the hot water freezing faster. Perhaps that antifreeze in the fluid helps with that?
     
  5. naterprius

    naterprius Senior Member

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    So, why doesn't it just heat whenever it detects fluid flowing through it? Why does it have to have a switch? This would require a redesign.

    However, why not just hook it to the washer pump? (Via relay if necessary) then it will heat whenever you spray.

    Nate
     
  6. eagle33199

    eagle33199 Platinum Member

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    <div class='quotetop'>QUOTE(ttabbal @ Dec 7 2006, 02:33 PM) [snapback]359002[/snapback]</div>
    The freezing point is just that - the freezing point. for pure water, it's 32 degrees F (0 degrees C), add in anti freeze and other additives, and that level changes. So i think SeaSalsa was just trying to be funny, as the liquid when freeze whenever it (meaning the liquid) reaches that pre-determined temperature - hot water takes longer to cool down.
     
  7. ttabbal

    ttabbal New Member

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    <div class='quotetop'>QUOTE(naterprius @ Dec 7 2006, 02:04 PM) [snapback]359020[/snapback]</div>

    Because it needs a little time to heat the fluid. About 30s is enough, but it can't heat it as fast as you can spray it. Not connecting it to the washer pump is nice in that it doesn't require any splicing or cutting of the stock wiring harness. I wouldn't have installed it if I had to do much of that.

    It also has 2 modes, one to keep the fluid hot, another that has a spray pattern that is supposed to de-ice the windshield. You hold down the switch longer to get the auto mode.
     
  8. seasalsa

    seasalsa Active Member

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    <div class='quotetop'>QUOTE(eagle33199 @ Dec 7 2006, 01:30 PM) [snapback]359040[/snapback]</div>
    No, I was quite serious. I agree with your freezing point comment, it's just that hot water will reach that point faster than cold. The fact that hot water freezes faster than cold has been known for many centuries. The earliest reference to this phenomenon dates back to Aristotle in 300 B.C. It is known as the Mpemba effect.
     
  9. jayman

    jayman Senior Member

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    Canadian Tire was heavily advertising a similar product last winter. Too bad it had defective wiring and caused some truly spectacular car fires ...

    A handful of car makers include heated washer fluid as standard, but these are very expensive luxury EU suv's and sedans.
     
  10. Tideland Prius

    Tideland Prius Moderator of the North
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    Really? I've only heard of heated washer nozzles like the VWs and some Volvos?
     
  11. qbee42

    qbee42 My other car is a boat

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    <div class='quotetop'>QUOTE(seasalsa @ Dec 7 2006, 04:22 PM) [snapback]358995[/snapback]</div>
    Under some conditions this is true. It's call the Mpemba effect.

    Tom
     
  12. eagle33199

    eagle33199 Platinum Member

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    N3ever heard of it before, but doing some readings online, it seems to apply to how a body of water cools - IOW, something inside of a container. It doesn't seem like any one hypothesis for why has been fully proven yet, but here are some of them:

    1. better conduction - frost on the outside of the container melts due to the higher temperatures, then refreezes, making better contact (and thus conduction) with the cold surface the container is on.

    2. convection and surface ice - a thin layer of ice on the surface may slow down cooling - convection currents from hot water will melt this layer of ice, allowing for faster cooling of the body of water.

    3. Evaporation - Like sweating, evaporation draws heat from an object. there's more evaporation from warm water than cold, so it cools faster.

    4. Poor conduction and evaporation - The container used matters - if it conducts heat poorly (like the wooden buckets used by Mpemba), then more of the cooling can be attributed to convection and evaporation.

    5. Dissolved gases - When water is heated, impurities from dissolved gases are driven out, giving the water a higher freezing point


    Definitely a very interesting reading... now i want to go home and fill my ice cube trays up with cold versus hot water and see which one freezes first!

    But despite all that, I think only 3 and 5 could possibly apply. All the others don't really apply - with no container, 1 and 4 are thrown out. With relatively small bodies of water (and just a thin layer of it on the windshield), 2 can be thrown out.

    Evaporation is an interesting area. I'm sure much evaporation takes place as the water is flying towards the windshield. However, if there's a layer of ice/snow that you're melting, i would think conduction and the mixing of the fluids (freshly melts ice and the hot water) would do much more to change the temperature than evaporation (perhaps enough more to completely dwarf the cooling done by evaporation?)

    Dissolved gases is another interesting area... It doesn't sound like the water is being heated terribly much - at least not enough to produce visible steam. So one would have to wonder if this plays much of an effect in this situation.

    One other thing to consider is the makeup of the liquid. Everything i've read has referenced this effect to water - there's been no statement saying it's a water only phenomenon that i've seen, but since it is a bit questionable. We know that water is pretty peculiar in many ways (for example, it expands as it freezes), it could very well be that other liquids (like anit-freeze and washer fluid) don't suffer from this effect.

    Thanks for bringing this up seasalsa... you learn something new every day.
     
  13. seasalsa

    seasalsa Active Member

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    <div class='quotetop'>QUOTE(eagle33199 @ Dec 8 2006, 07:36 AM) [snapback]359280[/snapback]</div>
    There is a video on the Microheat site that shows a lot of steam, evidently they use a shot of steam to thaw the nozzles.

    The Mpemba effect seems to apply to any liquid, it was proven using ice cream.
     
  14. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Dec 7 2006, 11:13 PM) [snapback]359136[/snapback]</div>
    My co-worker drives a 2006 Range Rover HSE and claims heated washer nozzles, even for the headlamps. Others have made similar claims about their Mercedes Benz and BMW cars. Not sure if I can verify that right now, took early off work to do errands and then off to the hobby farm for the weekend.
     
  15. Tideland Prius

    Tideland Prius Moderator of the North
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    <div class='quotetop'>QUOTE(jayman @ Dec 8 2006, 11:16 AM) [snapback]359411[/snapback]</div>
    He's probably right haha. He has a heated steering wheel too.

    So far, it's limited to European cars.
     
  16. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Dec 8 2006, 04:43 PM) [snapback]359492[/snapback]</div>
    Jon

    Are you pulling my leg??

    jay
     
  17. seasalsa

    seasalsa Active Member

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    Google provided this info on the Range Rover HSE.
    LUXURY INTERIOR PACKAGE -inc: heated front/rear seats, heated steering wheel, heated washer jets. Gotta have some reason to justify a MSRP of $61,050.
     
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    <div class='quotetop'>QUOTE(jayman @ Dec 10 2006, 03:43 PM) [snapback]360154[/snapback]</div>
    No. seasalsa proves my statement.

    Here's another fact:

    The armrests for the front seats are also height adjustable so that they'll always fold down at the right height no matter how tall or short you are.

    Anything else you'd like to know? :D
     
  19. jayman

    jayman Senior Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Dec 10 2006, 09:20 PM) [snapback]360204[/snapback]</div>
    Jon

    I drove it most in July and August, so the last thing I could have thought of was a heated steering wheel in +38 C temps. Once my co-worker gets it back from the collision place, I'm going to have to take it for a spin and try out a hot steering wheel.

    Never used the armrests, always left them up. Though a height adjust sounds like a good idea to me.

    Hope you're surviving the winds/rains etc

    jay
     
  20. Tideland Prius

    Tideland Prius Moderator of the North
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    <div class='quotetop'>QUOTE(jayman @ Dec 11 2006, 06:01 PM) [snapback]360688[/snapback]</div>
    lol. Yeah, give it a shot.

    Yeah, we're doing ok. No power outage yet. Branch nearly crushed my neighbour's car. The branch was large enough that from afar, I thought a small tree fell over.