How To Plumb Electric Water Heater With Oil Indirect?

[maple1]

Can't you just set the boilermate hotter then?

 

[Beauly]

Can't you just set the boilermate hotter then?

hotter then what? or did you just mean, "Set the Boilermate to a higher temp"?

Not sure exactly what you mean. Even now, yesterday, running wood stove in house, the radiant is not calling for heat, yet the Boilermate will and so on come the the boiler, running away to heat the Boilermate to whatever temp I set, and meanwhile the EHWH (electric hot water heater) is full of hot water. It would be great to only have the boiler mate be able to call for hot water if the boiler was already running for heat. That is the trick, I think.

 

[maple1]

Yes - I was also thinking of the above suggestion to have the boilermate call only when there is a call for heat. Which should be often enough that the boilermate should be able to be heated as hot as you would want, once heating season gets going. DHW is a very small portion of an overall heating load. Plus the hotter you set the boilermate, the more hot water you have available overall, and the less chance of the electric having to be used at all.

But worst case if the boilermate isn't even used at all, electric DHW is pretty economical overall on its own. And re. legionalla, I think as long as the water gets hot enough before it heads for the taps (i.e. in the electric heater), the bacteria won't survive.

 

[Beauly]

Ok,

That is the goal then, setting up the Boilermate so that it can only be "allowed" to come on when the boiler is already at some temp above "cold". hotwater heater thermo switch taped to Boiler, only allowing Boilermate to call when Boiler is already hot.

I have an Everlast HTP EHWH (otherwise know as worlds most expensive electric hot water heater) which is quite efficient and insulated very well, so I am still spending less in electric than I was when the 165k boiler ran for 45 mins each time the Boilermate called for heat!

 

[velvetfoot]

With that heat sensor taped to the boiler plan you can probably set it so that it extracts more heat from the boiler after it shuts down rather than going up the flue. Although, with radiant and its lower temp requirements... Speaking of that, the oil version of this gas vent damper has been working well for me: http://www.supplyhouse.com/Field-Controls-GVD-6PL-6-Automatic-GVD-Vent-Damper-11703000-p

I have several Ranco digital controllers and like them: http://www.supplyhouse.com/Ranco-ET...ntrol-w-Sensor-120-240V-Input-Includes-8-Cord
They have 120/240v and 24 v. powered models. Even if it's powered by 120v, it can still switch 24v.

 

[Beauly]

With that heat sensor taped to the boiler plan you can probably set it so that it extracts more heat from the boiler after it shuts down rather than going up the flue. Although, with radiant and its lower temp requirements... Speaking of that, the oil version of this gas vent damper has been working well for me: http://www.supplyhouse.com/Field-Controls-GVD-6PL-6-Automatic-GVD-Vent-Damper-11703000-p

I have several Ranco digital controllers and like them: http://www.supplyhouse.com/Ranco-ET...ntrol-w-Sensor-120-240V-Input-Includes-8-Cord
They have 120/240v and 24 v. powered models. Even if it's powered by 120v, it can still switch 24v.

I do have radiant, but boiler still heats to 180f etc and then radiant heat goes through a mixing valve etc, as I do have two (small) zones of high temp, one for an office space on North corner of first floor with cathedral ceiling and sunlights and 6 foot patio door to deck, that room is not heated enough from radiant so I added a panel rad to the North wall, and then other zone is the fin tube baseboard on 2nd floor bedrooms that is seldom used)

But thoughts for heat sensor:

put that electric hot water thermostat in series with the aquastat on the indirect water heat -

install it on the supply pipe coming directly out of the boiler - strap in on, insulated it well.

wiring: disconnect one of the leads leading to the boiler mate (from the indirect aquastat), tie one to one terminal on the added aquastat , tie the other terminal back to the boilermate.

set the "supply aquastat" for about 140, set the indirect aquastat for about 100F.

When the boiler reaches 140F if the indirect is calling for heat it will then heat to its setting.

Thoughts?

 

[maple1]

I don't think an electric heater stat would work - it would be closed at lower temps, and it would open when it gets to setpoint (hot). I think that is the opposite of what is wanted?