Need help wiring tekmar 4-way controls

ThatF_inGuyInNY

The diagram shows the system im building. It uses the existing cast iron rads but adds a low temp manifold for underfloor heating.

I was going to run the boiler loop pump off the system pump control on the tekmar 360. Then run the end switch from a tekmar 304P circ pump relay to the mixing control input demand. But this will run the boiler loop pump on a DHW call. Ideally, I would like a call for DHW to trigger only the DHW pump. I was also going to connect the boiler output control on the tekmar 360 to TT on the boiler. The boiler is a weil-mclain WGO with Hydrostat.

Is there a better way to control this? The tekmar manual states "Note: The boiler pump should not be operated by the boiler’s aquastat, as this may lead to
improper cycling of the boiler because of inconsistent flow past the boiler return sensor" So I think I may be stuck in this configuration. Does it even matter if the boiler loop pump runs on a DHW call? The mixing valve output sensor would not be satisfied during this time (since none of the heating circs will be running) but maybe thats ok.

NOTE: The tekmar 304P relay pic is just a screenshot from the manual, not the actual configuration. Mine would have the DHW circ in priority, the low temp circ (for floor heat) and high temp circ (for radiator heat).

STEVEusaPA

Well, how is the boiler piped?

ThatF_inGuyInNY

STEVEusaPA said:

Well, how is the boiler piped?

Primary/secondary, closely spaced tees just like this

hot_rod

Unless it is built into the tekmar you could just use a RIB relay to drop power to the remote enable on the tekmar, when the indirect calls.
Although it is useful to have a timer function also so you don't stick on an indirect call if something goes wrong and not get heat. Maybe RIB has a timer version, check their site.

STEVEusaPA

What I was getting at with the piping is where is the piping showing the dhw? If it's off the other side of the boiler you can do it with a different Tekmar boiler control that won't turn on boiler loop.

109A_5

Hello @ThatF_inGuyInNY,

Do you already have the Tekmar 360 and 304P ? If not wouldn't you be better off with the Tekmar 403 ?

Although not impossible I don't think Tekmar intended to have the 360 and 304P married together.

If you already have them and using the piping diagram you provided above, I would run the boiler pump with the 360 and wire it up this way.

ThatF_inGuyInNY

109A_5 said:

Hello @ThatF_inGuyInNY,

Do you already have the Tekmar 360 and 304P ? If not wouldn't you be better off with the Tekmar 403 ?

Although not impossible I don't think Tekmar intended to have the 360 and 304P married together.

If you already have them and using the piping diagram you provided above, I would run the boiler pump with the 360 and wire it up this way.

Thank you for this. I did not know the 403 existed. I do not have either but was about to pull the trigger on a big order from supplyhouse. I had it originally designed with taco i-series and taco switching relays. Then the i-series went backorder and I figured why not go tekmar.

Anyway, I glanced at the data sheet briefly, it looks like this would replace both the switching relay and mixing control, that seem right?

109A_5

Hello @ThatF_inGuyInNY,

ThatF_inGuyInNY said:

Anyway, I glanced at the data sheet briefly, it looks like this would replace both the switching relay and mixing control, that seem right?

Yes, IMO, Except the tekmarNet ® 2 (tN2) only thermostats, which could be a show stopper for the 403.

As I was looking up I/O manuals for the 360 and 304P, I looked at the Tekmar's web site. https://www.watts.com Went to "Products" then under "HVAC & Hot Water Solutions" on the right side of the page clicked on "Controls". Then just picked filter check boxes, Mixing = Yes, DHW Control = Pump, Zone Operation = Pump which seemed to best fit your application and the 403 was the only option left.

Looking at the wiring diagram it looks like it has all the blended features of the 360 and 304P married together, and more, except for the tN2 only thermostats. Too bad the thermostat type is not menu selectable.

The combination of the 360 and 304P and a DPDT Relay may be a bit less expensive than the 403, but the 403 may be a bit simpler to install and understand (no odd relay interface to make the two work together).