Thermistor Boilermate vs HTP

[Ordie]

Installing a UFT-80w Boiler, it states to use HTP 7250P-325 Thermistor in DHW tank, if I use my existing Boilermate can I use the Thermistor 2704-259 that's already installed in it and connect it to the HTP Boiler or do I need HTP Thermistor?

http://www.amtrol.com/wp-content/uploads/2017/09/9040-586-08_17-BOILERMATE-IO.pdf
http://www.htproducts.com/literature/lp-542.pdf (page 9)

Or should I just install the DHW tank as a priority zone off the CH piping, and skip piping as it is shown in the HTP install guide? What about boiler modulating?

 

[NY_Rob]

From the link you provided it looks like the Boilermate uses an Aquastat vs. a simple thermistor probe.

You would connect it to the "DHW Temp Sensor" terminals at the boiler then select "Aquastat" vs. "Sensor" in the boiler install menu (item 39:SA).

The boiler generally won't modulate for DHW production as you typically use 180F water to heat the DHW, and the DHW tank when properly piped (1" copper) with a right sized pump can take the full 80K BTU output of the boiler with no need to modulate down.

You shouldn't pipe the DHW off the CH water as a priority zone... what happens when the outdoor temp sensor is telling the boiler to heat your house with 120F water... you'll never heat the water in the DHW tank with 120F water.

Pipe the DHW tank on it's own zone so you can give it the 180F water it needs... and use the aquastat you already have.

 

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[NY_Rob]

PS... is this a self install or will a HVAC company/tech be installing it?

 

[Ordie]

From the link you provided it looks like the Boilermate uses an Aquastat vs. a simple thermistor probe.

You would connect it to the "DHW Temp Sensor" terminals at the boiler then select "Aquastat" vs. "Sensor" in the boiler install menu (item 39:SA).

The boiler generally won't modulate for DHW production as you typically use 180F water to heat the DHW, and the DHW tank when properly piped (1" copper) with a right sized pump can take the full 80K BTU output of the boiler with no need to modulate down.

You shouldn't pipe the DHW off the CH water as a priority zone... what happens when the outdoor temp sensor is telling the boiler to heat your house with 120F water... you'll never heat the water in the DHW tank with 120F water.

Pipe the DHW tank on it's own zone so you can give it the 180F water it needs... and use the aquastat you already have.

The boilermate has a aquastat with a Thermistor 2704-259 plugged into the back of it, I was thinking of unplugging it and wire the thermistor directly to the boiler, didn't realize I could just select Aquastat on the boiler, that makes it simple.
The Boilermate I have is 3/4 inch, I'll probably pipe over 1 inch then reduce to the 3/4 inch, that way if I upgrade the DHW Tank later on I'll have the 1 inch pipe. I have a Taco Viridian VR1816 Pump on hand that I could use for the DHW.
I agree with not using the DHW on its own zone, the modulating boiler will lower the water temps.

 

[NY_Rob]

Sounds like you have a solid plan!

Just leave the pump on a fixed speed setting....

 

[NY_Rob]

You know... you could use the correct HTP sensor in the immersion well that's in your Boilermate.
You can get it on ebay for about $30....