Separate Indirect DHW signal from Taco SR503

yuwei24

I have a new Lennox gas fired boiler installed recently. An HTP indirect Hot water tank was installed at the same time. There are two zones and the third DHW priority zone and they are all controlled by the Taco SR503 relay. The boiler comes with a Hydrolevel Hydrostat 3000 controller, which has smart Economy setting that can reduce the boiler high limit based on some built in algorithms. It also provides a bypass feature to allow bypassing the Economy setting if the DHW calls the heat. In order to trigger the bypass it needs a separate signal fed from the Indirect DHW. My DHW has already been connected to SR503 priority zone and the contractor didn’t wire the separate signal to the Hydrostat control. As a result, my DHW heat call is treated as a regular zone heat call and runs at a lower temperature. May I know in this case what is the best solution to add the separate DHW signal to the Hydrostat? I read something about adding a relay but not sure what kind of relay and how should it be wired.

I am really new to all these. I have been reading posts in this great forum but unfortunately wasn’t able to find a lot information about Hydrolevel.

Many thanks in advance.

yuwei24

With the Economy feature turned on, my boiler’s high temperature limit various between 145F to 170F, the low temperature limit seems to be consistent 125F. Though my DHW is wired correctly to the priority zone in Taco SR503, the 145F boiler water takes too long to satisfy the target temperature which is now set at 130F. It was originally set to 140F and that took even longer. If the Economy is bypassed, the boiler will run at full power. The high will be 180F and low will be 170F.

Jellis

Hi Yuwei, your zone 3 priority is turned off on your board. I assume zone 3 is your DHW tank.
with that "zone 3 priority" turned off it is not treating zone 3 as a priority but as another zone. turn it on and you should get better DHW recovery time.

HVACNUT

Do you have that relay that you posted on the boiler?
If so the indirect thermostat is
in cable 2. Green and white.
I've never wired the 3000 but it looks like an isolation relay is needed.
You'll have to find out which is the load side of the indirect thermostat. Green or white? The load side will energize a (field supplied) 24v, single pole N.O. open relay as well as completing the circuit back to the 3000. The N.O. contacts will go to R-W on zone 3 for the indirect.
Set your economy. You can leave the priority switch off on the SR503.
I downloaded the 3000 manual. Unless I'm not seeing it, they dont show that which is a shame.

yuwei24

Jellis said:

Hi Yuwei, your zone 3 priority is turned off on your board. I assume zone 3 is your DHW tank.
with that "zone 3 priority" turned off it is not treating zone 3 as a priority but as another zone. turn it on and you should get better DHW recovery time.

Hi Jellis, the Priority switch in Taco was turned on and working fine. When DHW calls for heat, the rest zones won't run. The problem is Hydrolevel 3000 cannot tell if it's a priority heat call or a regular call, hence it's running on a lower temperature.

yuwei24

HVACNUT said:

Do you have that relay that you posted on the boiler?

If so the indirect thermostat is

in cable 2. Green and white.

I've never wired the 3000 but it looks like an isolation relay is needed.

You'll have to find out which is the load side of the indirect thermostat. Green or white? The load side will energize a (field supplied) 24v, single pole N.O. open relay as well as completing the circuit back to the 3000. The N.O. contacts will go to R-W on zone 3 for the indirect.

Set your economy. You can leave the priority switch off on the SR503.

I downloaded the 3000 manual. Unless I'm not seeing it, they dont show that which is a shame.

Hi HAVCNUT,

Thanks so much for the answer, I don't have the relay yet but I guess it is a normal N.O relay and can be easily found in ebay, am I right?

My Cable 2 is slightly different to what's described in the latest manual. It doesn't have Green and white wires but two Brown wires. I called the Hydrolevel support and he said it's the same. Is that right?