Gv90+ DHW

Twodogs

Replaced a leaking UB90 HX that was 16 yrs old with a GV90+4.

I installed this unit myself using the 1.25" headers with 1" pipe, for the primary and secondary loops.  I have 4 pumps on the header, 3 that feed the copper slatfin, and one going to the Amtrol indirect hot water heater.  I've wired the three pump relays in parallel to the TT wires on the boiler.  If I wire the indirect DHW relay to the blue DHW wires on the boiler, when that zone calls for heat, will the boiler fire to 180 or do I need a 4 zone controller to do this?  I realize the other zones will not lock out since I have individual pump controllers, which I'm fine with, just want the boiler to rise from 140 to 180 with a DHW heat call.  Thanks.

109A_5

Hello @Twodogs,
You could do it with a relay. If you want DHW priority, you could use a DPDT relay to also open the TT control path through the paralleled zone relays during a DHW call. Many folks like the independent zone valve or circulator controller box since it usually simplifies the wiring and has the DHW priority built in, also status indication.

Twodogs said:

just want the boiler to rise from 140 to 180 with a DHW heat call.  Thanks.

As long as that is what that boiler controller board is programed for when the DHW (blue wires are closed)

HVACNUT

Since you have separate relays for each circulator (not a zone panel), then wiring the end switch (XX or 5,6) on the relay for the indirect to the Blue wires on the boiler will override the economy setting and run the boiler to high limit for DHW production.

hot_rod

Is the boiler large enough to run the 3 zones and cover the indirect?
The DHW priority is to allow the indirect to take most or all of the boiler output to recover the load quickly and get back to heating loads.
It depends on how you have the indirect piped and pumped also, whether it can use all the boiler output.

Twodogs

Hello
 I have the indirect water heater tied into a Honeywell RA832A relay.  The XX terminals coming off this relay have continuity when there is a heat call, and remain open when temp is reached.  This relay was originally wired in parallel with the three slat fin zone pump controllers.

It is time to remove the DHW pump controller from the parallel setup, and rewire for DHW priority. Looking
 at the wiring diagram on p58 on the GV90+ manual, blue wires go to the DHW aquastat.  Does this mean I need to run wires from the TT terminals on the DHW pump controller to the boiler's blue wires?

What has me confused - one of the blue wires is factory spliced to one of the black TT wires.  

Or do I take the XX wires from the relay and connect to the blue wires.  To me, this makes the most sense since XX would close with a heat call, but not sure what the IBC is expecting on the blue wires.

Thanks

109A_5

Hello @Twodogs,
Seems like the splice is intended to be there.



I would just connect it up like the manual instructs. And make sure the correct circulators are working when needed.

Twodogs

HVACNUT said:

Since you have separate relays for each circulator (not a zone panel), then wiring the end switch (XX or 5,6) on the relay for the indirect to the Blue wires on the boiler will override the economy setting and run the boiler to high limit for DHW production.

I have the wires coming off the XX terminals of the DHW pump relay, wired to the blue wires going to the IBC.  When the Amtrol Boilermate calls for heat, pump kicks on, and boiler fires, however, only fires to the set temp of 160, then shuts down while there is still an active heat call.  Checked, rechecked wiring, it is identical to the diagram.  Is there a dip switch setting I might be missing, didn't see anything in the manual.  Thank you