Windy Days = Cold Showers! Why?

[valterra]

It's been windy as heck here the last few days.  Temperatures in the 60's and 70's, so very nice days.

However, when the wind is really blowing, I always get a significantly cooler shower than non-windy days.  Not COLD, but not burning hot like I usually like.  

My shower dial goes from about the 8 o'clock position (HOT) to 4 o'clock (COLD).  On a normal day, 12 o'clock or 11 o'clock is perfect and hot.  10 o'clock will peel off your skin.  (Just kidding - but it'll turn you red for sure).  Of course, over the course of the shower, I have to keep cranking that dial ccw as the hot water runs out.

Today, another very windy day, I had the shower on the 8 o'clock position the entire time and it felt just barely warm.  That's full-on hot, meaning that as the hot water runs out, it's cold shower time!!!

Any thoughts on why this happens?  Don't tell me I can supplement my Domestic Hot Water with wind power.  lol.  Trust me, I've thought about it plenty.  The wind isn't cold, my pipes aren't exposed, the downstairs (where my hot water is) is not noticeably cooler than any other day.  It is a beautiful, windy day outside, but the water is cooler.

Any thoughts?

Oh - I heat my water with Propane.  Giant (500 Gallon?) tank outside.

[luckeydog]

Is it possible that the wind is blowing down your exhaust flue? what type of pilot do you have in you water heater? is it electronic or flame?

just seems that if it is wind causing you hot water to cool down either your heater is not keeping the flame lit or the wind is cooling you water heater through the exhaust flue.

[valterra]

That is very interesting.  I believe it is a flamed pilot.   I will go check.

As far as cooling off through the exhaust - on windy days it does tend to suck the water out of the toilet bowl a little, too.  That would be the same thing - wind blowing straight across that big piece of PVC pipe on my roof.

[valterra]

I guess what it comes down to is How can I solve this?  I'm thinking that putting screening or anything else over the holes of the flue could prevent it from working correctly.  I mean, the wind blowing around and through it is what makes it work.  The is just TOO much wind.

It is a gas pilot.  Downstairs, I can hear the wind buffering the vent for the water heater / HVAC (same large tube).  When the wind blows, the pilot light doesn't flicker.  

My vent / flue thingie is a piece approx 5 inch metal tubing that sticks out of my roof by about 3 feet.  On top is a cylindrical piece that sort of looks like a VAWT.  It does not move and has 3 or 4 vertical slits cut into it.  

I can take a picture if it would help.

[Airstream]

Take a look at the flue cap accessories offered here for ideas - these are sold for wood-burners on on a boat; if there is anywhere you don't want the stack gasses to be reversed it's in a wooden boat 100 miles from land... I have one similar to the coffee can looking one on the rooftop chimney stack.

http://www.boatownersworld.com/dickinsonmarine/newport_solid_fuel_heater.htm

I believe a hot water tank must have no damper itself: maybe now the question is what else is connected to the same flue?

We have an automatic electric motorized damper on the main flue just above the furnace, the water heater intercepts that run just before it enters the masonry chimney so there is zero airflow PAST the DHW flue inlet; the hot water heater has a small pyramid shaped back-draft baffle just as it comes out of the insulated tank; if that is missing the hot gasses would escape too rapidly and efficiency would be lost on burn cycle AND have excessive convection cooling when the burner wasn't running.

[JW Peters]

I use a rooster tail. It looks like this. http://cgi.ebay.com/Copper-Patina-Chimney-Flue-Weather-Cover-Cap-10-x-10_W0QQitemZ170140300412QQcmdZ
ViewItem                                               It turns the opening out of the wind. Also outside air needs to enter the area where the heater is located for combustion and the draft flow. JP

[vawtman]

Valterra,

 Is your shower located outside If so the wind would make it feel cooler.If not i would say you need a new heater.The thermostat should regulate things wind or no wind.

 Just my thoughts

[valterra]

Is it possible for the thermostat to "kind of" work?  Because the heater sure does a bang-up job of making water hot on non-windy days.  :-)

After I move the shower back inside, I will test further.

Thanks for all the suggestions, guys.  The "rooster tail" idea seems interesting.  Us wind genny guys should be familiar with the concept of its operation.  :-)

[mixerman]

Be sure the water tank is filled all the way (no air traped), trip relief valve , should get water instently!, could it be possable that you have a slow leak somewhere. Maybe lime buildup on T-stat. Just a few thoughts.