Price 'em yet? I wonder how 'dear' they are?

I did notice mention of them in the install for the control... pretty neat actually. Especially if the control is able to 'average' them and do control based on that...

Thing about indoor sensors is that the extra data input to the controller adds a whole new 'dimension' to the control's 'thinking'. The circs will tend toward constant circulation, and the system will vary the water temperature to control the room temp. Of course you will still be limited by the partial ODR range...

How long before you ask: "What do I have to do to convert piping to allow FULL ODR?"

I noticed that on my first read through... and wondered why there needs to be a different sensor? My perception was that it was the same sensor, just placed differently.

I didn't understand the need for EITHER a DHW or RETURN sensor... but maybe after a few more reads, it will start to make sense. Why not run the DHW with an aquastat control firing the boiler? Then you could leave the return sensor at the boiler? I mean, the DHW has no need for temperature control... all the control really needs to know is "Is there a DHW heat call?" an aquastat could tell it that and fire the boiler to high limit until the DHW call is satisfied... curious why they would do it that way.

 

Luckydriver-
Good to know I am not the only crazy one out there!

Trooper-
It looks like you can get the non-programmable one online for about $90

You're right. It is the same sensor. I guess the installed never realized it because I had to wait for him to bring another sensor for the water heater. If we knew it could only handle the return temp or the DHW he could have just moved the thing.

My thoughts exactly. The return temp is more important. Dont get me wrong, it was nice to be able to digitally set the DHW to 125, but I will probably never change it again. There are some other settings in there like when the unit is in vacation mode, you can set the DHW as low as 60 degrees. Again, nice but not crucial. And I would need to manually switch to vaca mode, so I might as well just turn down the DHW aquastat. I cant get a handle on their thinking with this. I am bummed it can't handle both, but since I need to choose I think knowing the return temp more critical. Now I have to call the installer and the DHW aquastat back. I didnt know he swiped it.
Here's a question. After I hookup the return sensor again. Once I get the ODR dialed in and am comfortable that the return temp is good an not dropping below 135, could I then switch back to the DHW sensor? Or does it constantly need to be monitored? Just wondering. Thanks.

 

I guess you could switch it back, but I really don't see the point.

Still haven't had a chance to re-visit the manual... been 'down' with the flu past few days...

 

You may want to bump up the DHW tank temperature a little. And for vacation mode keep the temperature high.

The reason is that Legionella bacteria will grow up to about 120 F (about 68 F on the low side), and live but not grow up to about 130 F. Once the water is above 130 F they start to die. The thing is that the bottom of the tank tends to be cooler then the water above it. So don't want to provide a breeding ground for them.

Al.

 

Will do. I didnt know about the bacteria. Thanks.

Trooper, Hope you feel better. This forum needs you!

 

Much better, thanks...

Yeah, that Legionella is not a good thing...

What I know about it is that it's not dangerous if INGESTED, it's killed as soon as it hits your stomach... it's when it's INHALED that you have a problem... like in a nice steamy shower...

If you are going on a long vacation, and want to save a few bux on the hot water... when you return, flush the water heater, and then turn up the temp to at least 140 for at least two hours before use.

One of the reasons that many codes now require tempering valves set at 120 on ALL water heaters is because of the bacteria thing... I believe that current 'state of the code' is for water heaters set to 140 with the tempering valve at 120.

 

trooper i'm glad i read your post after oldboiler's. because my installer told me if just going away a day or 2 in summer keep the unit on, but if i'm going away a week, kill the emergency switch if i want to save on oil that week. reading about the bacteria scared me but now that i know i can empty the smart 40 tank and just let it cook for 2 hours with fresh water, i feel better. But he didnt tell me anything about flushing the tank, just inferred i could come home and fire it up and use the water. I guess he doesnt know about the bacteria

if course the liklihood of me having money to take a week vacation after my boiler bill is slim anyway

 

First off, MOST city supplied water is relatively free of 'breeders', and chlorinated, and in most cases there would not be a problem.

If you are as paranoid as I am, and/or have non-disinfected well water, by all means do the 'flush' thing... You really don't have to 'empty' the tank, but it can't hurt... and if you want to be REALLY sure they all daid, go to 150 ... also, after doing so, run every hot water tap in the house until you are sure you've flushed any water that was standing in the pipes...

If you've got an older home in which lead based solder was used to join the pipes, you should probably also flush the cold... see how paranoia grows?... it's a virus all on it's own!

 

I don't know what you mean by empty the tank, but if you are talking about draining it - DON'T.

To do so, you need to drop the boiler water pressure low enough that it won't collapse the inner hanging tank that has the fresh water. The fresh water in that tank keeps it from getting crushed like a can in NJ Trooper's hand.

Besides, you can't drain a tank-in-tank design down all the way ('cept the smaller Euro inverted versions) so the water at the bottom of the tank below the dip tube will just sit there... with lots of air.

Just pull the wire plug on the water heater when you go away or spin the dial right down. When you return, turn the water up to 60C/140F and you're set.

I keep mine around 115 to 125 but once a week I crank it up. When I go away for more than a few days I shut the DHW off.