Will this work?

kev

Paul, I have used injection on a few radiant systems with good results. I am trying this design for first time and will let you know if its a success.The controls are where I get lost. Joe, where can I get that TACO control guide? Can my supplier get it from you? Never sure what to use where sometimes,
Thanks again.

kev

Will this work?

This is a proposed piping layout. I will be using a TACO 700-2 Boiler reset to control temps in fin tube baseboard heating loops. I'm a showing a DANFOSS 3-way valve to protect boiler.

Not sure where to place boiler senser: point A or B?

If I use the ZC-ZR tabs on the SR 504 to power the circulator for boiler in heating mode, how should I control the boiler and circulator for DHW call?
Any suggestions as far as piping or control plan would be apprieciated.
Thanks.

frank_25

You haven't read Dan's "Pumping Away", that's first; Second is I'd use TRV's or zone valves before using all those circs. But of course that's me. Over forty years in the business, what do I know?

kev

I am pumping away?

Using circs will give me the most control over the flow to each zone cost is secondary. I most concerned will control strategy.

Paul Rohrs_5

Taco Control Wiring

Check page 24 of this Taco wiring guide. You might have to upgrade to the expandable (EXP) version of your SR504, but this should get you there.

As for DHW, I would wire the aquastat leads to the Zone 4 priority terminals if that is what you are after. Taco makes good stuff and this PDF form is available in their tech library.

You might also check out Tekmars TN4 equipment for future jobs and see what that might offer for pricing and control features.

Regards,

PR


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Jamie_5

control and return temps

Disclaimer: not a professional.

It looks to me like you are pumping away. The primary loop pumps are right after the expansion tank. The boiler is a secondary loop.

Depending on the length of the loops and pipe size, etc., though, I don't see why you'd want to use so many circulators. The other poster's suggestion for zone valves or TRVs makes sense to me.

I'm also not convinced that your control strategy is good. It seems to that if you're using full boiler temeperature reset, the thermostatic mixing valve is not going to protect the boiler against return temperatures in the condensing range or will starve the primary loop of hot water. Of course, it depends on the relative volume and temperatures of the primary loop and boiler loop, but I bet an injection system or motorized four-way valve would work better. If you're only resetting down to about 140F, then I guess it doesn't matter.

As to sensor location, you are trying to control the water temperature the baseboard sees. Unless the flow in the primary loop is equal to the flow in the boiler loop at all times, put the sensor in the primary loop.

That's my take on it.

Paul Rohrs_4

Partial Reset

You can make it all work as you have drawn it with the corresponding Taco wiring as shown on page 24. It seems that you can only get a "partial reset" to the zone heating in that you will always be limited to the boiler minimum.

Consider adjust the PC700 control to the PC705 and use a variable-speed injection circulator to get full outdoor reset to the zones.

Here is a simple drawing. Check out page 26 of the Taco wiring guide to couple with this. Just a thought. The only thing to change other than the control would be to lose the ESBE mixing valve and add an injection circ.

Regards,

PR

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Joe Mattiello_2

The SR504-EXP, has the capacity for the PC700-2 outdoor reset control to simply plug in, facilitating the wiring. Apparently, you have a primary/secondary piping arrangement, so a primary circulator has to energize when there is a demand for heat. If you have the SR504-EXP, daisy chained to a slave board use the ZR terminal on the slave board to energize the primary circulator when there is a demand from any zone including domestic. As for positioning the boiler sensor, in my opinion, the system will operate more efficiently if the sensor is located in position A. My methodology is the boiler is non condensing, and you have a 140 degree ESBE valve to protect the boiler, so load reset makes more sense, and synonymous with your system dynamics.

Joe Mattiello
Technical Support Technician
Tel. 401-942-8000 X 484
Fax. 401-942-2360
1160 Cranston St
Cranston, RI 02920
joemat@taco-hvac.com