Aquahot 400D Question

[Chargerman]

If that’s the case then why would they have the electric at all. May be worth a call to Aquahot to understand how it’s supposed to work. Not on together all of the time just doesn’t make sense to me. I. And assure you mine does not work that way. If both are on Diesel only kicks in for showers or other high demand situations where the electric cannot keep up and mine only has one electric element

[Ann n Gene]

Don’t understand either but Entegra has told me on all four of our Entegras that is how they work,

[Chargerman]

After thinking for a moment after my last post electric would certainly make sense when you don’t have the Diesel button active.

[brobox]

Originally Posted by Ann n Gene

Don’t understand either but Entegra has told me on all four of our Entegras that is how they work,

Gene, like you, I am sure glad we have a manufacture that takes the time to explain our systems, put on classes, post Youtube videos and give us a complete folder of owners manuals.

[Marcosdad]

Ann n Gene is correct. There is no "electric priority". When the system falls below the temp threshold, both will fire if both switches are on. That's why I operate with electric only unless I anticipate a demand up with which it cannot keep. (Never end a sentence with a preposition)

[swberry]

Originally Posted by DeWat

AquaHot calls the electric element their secondary heating source.

Boom!! Exactly. That is right out of the aqua hot manual. This is the very reason I ran both electric and burner at the same time for a couple months after we took delivery. Then I decided to start using electric only (to save diesel LOL). Then after about a month I start noticing discoloration and a bit of sludge.

So resorting to troubleshooting 101 I try to figure out if there was something I did different before the discoloration started. I realize I had started to run on electric only. Now I decide to conduct an experiment; Remove the expansion tank and clean thoroughly, replenish with boiler fluid (century), go back to running both switches in the on position. So far two months later and no discoloration. Nada.

[DeeGee]

Originally Posted by DeWat

Also some fail to realize that the stir pump only works on diesel, so the boiler fluid still has the potential to "cool down" since it's not being circulated throughout the system on electric only.

That, I have not heard anywhere in the many AH threads. Very interesting. No stir pump could certainly account for the different effects upon the fluid.

[royals1212]

Does the 400D have a stir pump? The 400LP does not

[royals1212]

On the 400LP the circulation #2 pump also performs the tank stirring

[DeWat]

Originally Posted by DeeGee

That, I have not heard anywhere in the many AH threads. Very interesting. No stir pump could certainly account for the different effects upon the fluid.

This is from the AquaHot 450D service manual, but I don't think the 400D would be different concerning the stir pump (I reserve the right to be wrong): "In order for the stir pump to operate, the diesel-burner switch must be on...".

[voltdoc]

There is no dedicated stir pump on the 400D. The #2 circulator pump (bed/bath/basement heating loop) is activated and acts as a stir pump when the following conditions occur:

1. The burner switch is on.
AND
2. The low temp cutoff status light is NOT illuminated.

The above is on page 31 of the 400D service manual.

The purpose of the low temp cutoff thermostat is to shut down the heating loops when domestic hot water is called for to ensure all energy goes to heating the domestic hot water. In practice this means running a hot water tap will shut down the heat (if it was on) and allow the stir pump to activate.

The above is from page 25 of the 400D service manual.

This agrees with info provided by the AH trainer at homecoming last Spring.

There is also a jumper required on the control board on 400D models to enable pump #2 to operate as a stir pump.

[DeeGee]

Ah. I have a 450D, so there is a stir pump.

I typically use both the electric and diesel elements.