Indirect Hot Water Tank - Call for heat kill switch while away??

[Don2222]

Hello

My neighbor and I have a nice FHW oil boiler with indirect hot water tank.

We were thinking to save money while we are away on vacation or whatever, then why not put a simple SPST toggle switch in one line of the Aquastat sensor on the DHW tank to open the circuit? The boiler will still keep the house warm if needed but no oil will be wasted for heating the water tank for water not being used.

Has anyone tried this??

Any comments appreciated?

Thanks

 

[in hot water]

Sure. Does it have a temperature control aquastat on the tank, some have low, or vacation settings built right into the control.

If it is just a Honeywell aquastat turn the dial all the way down.

 

[Don2222]

Hello

It is a basic Honeywell Aquastat with a dial that goes from 120 to 140. So a nice convenient wall switch would be good

A better digital aquastat might be nice if it had the off feature. Turning the temp down to 120 would save but not as much as off especially in the summer time right?

 

[Tarmsolo60]

I put my fuel oil indirect control circuit on an intermatic brand lighting timer. I only let it fire for a couple hours in the morning, did this for a neighbor also. I'm usually on wood(unpressurized storage w/domestic coil) he is on oil all summer and says it saves quite a bit of fuel. You can turn off the program easily if you are going away and want no hot water.

 

[Don2222]

Hello

After speaking to my Tekmar 260 expert, I found that all I have to do is setup unoccupied mode with a toggle switch as a Home/Away switch. This will not only kill the DHW but also make other settings for even more energy savings!!

From the Tekmar 260 Manual !!

Unoccupied Switch
If an external timer (tekmar Timer 032) or switch is used, connect the two wires from
the external switch to the UnO Sw and Com terminals (13 and 14). When these two
terminals are shorted together, the control registers an unoccupied signal.

 

[peakbagger]

I have my indirect tank hooked into a programable thermostat. The tank is off line during the night time hours unless I override it. If I am out of the house for a few days, I just turn the thermostat off. The thermostat is in a heated space on the main floor so how I get it to work as a timer more than a thermostat is to set the occupied temp real high (I think 80 degrees) and the night temp at 50 degrees. I think ts pretty standard but make sure your inidrect heater is on a 24 volt control circuit as a standard thermostat is not going to switch 110 AC very well!

 

[velvetfoot]

I came close to doing this, https://www.hearth.com/econtent/index.php/forums/viewthread/21456/ , but of course never got around to it.
I actually bought an intermatic lighting timer (that goes into a box).

Do you guys really feel you're saving money with this?

 

[Tarmsolo60]

I came close to doing this, https://www.hearth.com/econtent/index.php/forums/viewthread/21456/ , but of course never got around to it.
I actually bought an intermatic lighting timer (that goes into a box).

Do you guys really feel you're saving money with this?

My indirect would kick on while washing my hands, it bugged the hell out of me. Three people in the house so it was always kicking on and running for 20 minutes. I think it saves alot of fuel, if it can only run 1 or 2 hours a day your not constantly reheating the boiler. I haven't tracked it because i rarely use my indirect anymore, my neighbor claims saving over 100 gallons in a summer and he's a very honest guy.

you don't have to save much fuel to pay for the timer, let it run an hour in the evening if morning isn't enough. It's the cycling during the day for reheating a few gallons of water that add up.

 

[btuser]

I have an output on my alarm panel that will put my boiler control into unoccupied mode. Whenever the alarm is armed (just away, not stay) the boiler will ignore a call for heat from the aquastat. I can also put the output on a schedule but that's too confusing. It works. How much I dunno, if you can do this yourself then its cheap but to send out a tech it would cost about $100-200 if you panel has the capacity. Even the cheap ones do. If your competent then you can do the wiring and your service company can call the panel and do the necessary programming. They should do that for free.

It saves more from the standby losses on the boiler than for the loss of temp on the indirect.

 

[Don2222]

Hello

Thanks everyone for all the great suggestions.

The timer and alarm suggestions are really good.

One other thing I should mention here is that the heat being pushed out of the indirect tank when the water is heated and expanded is being convected to all the hot water pipes in the house. This causes the boiler to come on alot more to heat the pipes even when noone is home!! So the first plan I used was to install a Heat Loop above the indirect tank on the DHW hot water output 3/4" line with a heat nipple. Then I installed a DHW Expansion Tank on the DHW Cold water line before it comes into the indirect tank. This has already stopped the boiler from comming on numerous times and when I do take a shower in the morning the water is sooo much hotter I can easily feel the difference!!

Tonight, I just finished putting in a toggle switch I mounted on the wall marked HOME or AWAY to put the Tekmar into unoccupied mode with the dip switch down so the DHW call for heat will not be satisfied when I am away. I can still connect it to the alarm panel but want to try it this way first.

Then put 1" fiberglass pipe insulation around all 3/4 inch and other pipes in the boiler system. Available only from a heating contractor supply house. Home depot has the 1/2 fiberglass pipe insulation for 3/4 inch copper pipe and charges more money for it!!

Now I have to see when the boiler comes on and how a timer can curb that further but I suspect there will be some loss in how hot the water is when the timer has the circuit turned off. I really like the idea of the timer only being on a few hours in the morning!!

I was using 45 Gallons of Oil per month, now I should be down to 20 Gallons per month or less. I will not be seeing the Oil man as much now!!

So thanks again everyone, the info is really good.

Take care

Pic below of Heat Nipples, Heat Loop and DHW Expansion Tank all purchased at Home Depot for Approx $60.00 !!