Adding indirect water heater, wiring relay

DLDL

I currently have 3 heating zones each with its own circulator with a taco sr503 relay (not utilizing the priority option) And a domestic hot water coil in my peerless 108k btu boiler. I want to add an indirect water heater. Do I need to get an SR 504 or is there a way to keep and wire up the Sr 503 and use the priority for the water heater? Thanks in advance

Leon82

Is your 503 expandable relay? If so I think you can ad a 501 and use the 503 priority for the indirect.

Does the boiler have its own dhw control?

DLDL

Thanks for replying! Not sure, here are pics if this will help.

DLDL

FYI a plumber friend of mine is doing the install next week, but he's on vacation right now. I want to have all of the material ready for him.

DLDL

If it helps everything was installed new in 2011

R Mannino

I would replace the dual aquastat with an Aquasmart or Hydrolevel and use that to drive the indirect circulator. It will save you some oil too.

DLDL

Would that mean switching the boiler to a cold start? If so does anything else need to be done as far as settings/wiring with the existing sr503 relay? Also would that allow me to have the indirect set up as a priority? Thanks

Eric_32

You can disable the lo-limit on that relay without buying a new aquastat.

If you don't, the boiler will still think it is making hot water through the tankless coil and want to maintain temp. Usually the lo is set at 160 and high on 180.

To disable your existing aquastat relay, and make it a cold start boiler, You will need a skinny flat screw driver and a small orange wire nut. Turn off the power to the boiler.

Looking at the control, you will see a white wire near the diff screw. Use the screw driver to depress the slot along side the wire while pulling on the white wire, to remove it out of it's spot.

Do the same thing for the Red wire closest to the LO dial, now connect these two wires together using the wire nut. Turn the power back on. The control will now only respond to a call from a thermostat or the indirect, and no longer maintain temp.

I think the easiest thing would be to replace the Taco mulit box with a 504 or 506-EXP one. Now you can run the indirect off the priority zone and you can add outdoor reset to it with a Taco PC-700.

R Mannino

You can set the new control to have the boiler "warm" start so it never goes completely cold. Terminals X-X in the SR503 would wire to T-T on the new control. To keep priority would require some rewiring between the SR 503 and the new control but it is possible.

DLDL

Thanks for the good ideas! So your saying to leave the tankless coil to preheat the water feeding into the cold inlet to the storage tank?

gennady

In my opinion you do not need indirect water heater, you need storage tank connected to the coil. Install aquastat on the storage tank to control pump. see attached.

R Mannino

gennady said:

In my opinion you do not need indirect water heater, you need storage tank connected to the coil. Install aquastat on the storage tank to control pump. see attached.

That does make the wiring easier!

DLDL

Only problem with that is I don't know if that will meet our HW demands. 5 people, 3 baths, 2 washing machines, 2 dishwashers. Was planning on getting a 45 or 60 gallon htp super stor. If 2 showers are going at the same time, that's 5 gpm so after 12 minutes the HW in the storage tank will run out and then basically we would be running directly from the tankless coil in the boiler, which can't keep up as it is. Any thoughts?

SWEI

If you take the path Gennady suggested above, you can use a conventional electric water heater as the storage tank. They're cheap enough -- go ahead and get an 80 gallon (or larger) if that's what you need. They also come with a thermostat that can easily be repurposed to run the circulator (a la @icesailor .)

DLDL

null
gennady:
In your illustration your using an indirect WH, no? Don't see how using an electric WH would work in this situation. You have the existing boilers tankless coil working as a replacement for the indirect WH zone. And then the cold and hot domestic lines connected as normal. An electric WH will only have 2 connections- cold in, hot out. Am I missing something here?

SWEI

http://forum.heatinghelp.com/discussion/142148/electric-tank-to-holding-tank describes the concept.

gennady

I actually showed storage tank, not an indirect fired water heater, storage tank has 4 connections on the bottom.
Just my 2 cents.

gennady

Electric heater piping

hot_rod

Also include a thermal expansion tank

DLDL

Spoke to my plumber friend today who's helping with the install. He recommends getting the expandable sr504 relay w/priority, eliminating the tankless coil, and going with the indirect set up the normal way. He's repaying a favor and not charging me labor, but obviously going this route will cost more for materials. If money wasn't an issue, (within reason) which option would you all choose? Also what size/brand tank would you go with considering my HW needs mentioned above?

Leon82

If you go that route you could use the 504 exp since you would only need 4 zones.

DLDL

Leon82Leon82
If you go that route you could use the 504 exp since you would only need 4 zones.

Oops I meant to say the 504

BillAllen

Wow all these comments! Okay I just finished the job and YES I did need an indirect the tankless was corroded and gone!
Anyway, Its up and running but why does the boiler circ continue to run when the SS circ runs and they both shuts together too.
The boiler circ is doing nothing it is not circulating anything just going along for the ride. Must be a way to wire the SR 504 so when a call to reheat the DHW only the circ for that is activated.

Paul48

We have no information, to form an opinion, and provide an answer. Is the boiler piped primary/secondary? What make and model boiler?