Adding indirect...

Lurkin' Murkin'

Yes - the updated 404 sheet shows very clearly how to wire the circulators. Somewhat tricky, but definitely do-able.

Tom S.

is it feasible...

It's me again, looking at real estate. Am very interested in a house that has an oil-fired W-M boiler (circa 1996) for FHW heating (3 zones, one for each floor), and has a tankless coil inside for DHW.

My question is whether or not it is feasible to add a fourth zone to this boiler to support an indirect water tank? Does that compromise the three existing zones? Is it a big deal in terms of replumbing things? Would I also need to have fancy controllers added that deal with priority etc?

Thanks for any thoughts,

Tom S.

Lurkin' Murkin'

If each zone has it's own circulator, it's no compromise. I would use a multi-zone circulator control (Taco makes a nice one), with the built-in priority for DHW - very easy to wire. You don't have to add the DHW load to the space heat load, and most oil boilers in normal sized residential buildings are oversized anyway. Check the nozzle size hasn't been reduced from the boiler rating specification, if any issues getting satisfied...

Tom S.

thanks...

I believe that there are zone valves, not circulators for each zone. Does that change anything?

Tom

Norm Harvey

Not really, Just install a taco zone valce control instead of a circulator control, the zone valve version also has hot water priority.

With hot water priority, no other zone is allowed to heat while the hot water is heating. Essentially focusing every available btu to heat your hot water.

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Guy Woollard

circ

I would recommend putting a dedicated circulator to that indirect to get the best performance possible. Relying on the heating system circulator is not always the best option. Besides, having a second gives you a bit of a failsafe: if the heat circ quits, at least the tenants will have hot water, and vice versa.

Guy Woollard
N.E. Regional Sales Mgr
Triangle Tube Corp.

Bill D._2

Sorry for..

the uneducated homeowner question...

If you put a dedicated circulator on the indirect, how is it controlled? Now you have a mix of zone valves for the heating zones and a circ for the indirect. Is there a controller for that situation or am I missing something (more likely the latter).

Thanks to all for your help,

Tom

brucewo1b

Tom

Taco makes a ZVRC404 or 406 that you can control up to either 4 or 6 zones, makes a neat package for the Zone Valve wiring and can also be used to control the circ for the Demand Hot Water Tank with or without priority.

Bob Bona_4

simple.

One zone valve or 10, they all have to end up making one contact for the pump that serves them (tt).

So, put aside the zone valve thoughts and think about the pump. In this case you have a pump that serves the ZV's, and when the indirect goes on, you will have another pump for that. Do not use another zone valve for the indirect. Response time is too slow, lower flow, etc. 2 pumps now.

Get a 2 or 3 zone circulator relay panel with priority, i.e. Taco 503 and you're good to go.

Tom S.

Thanks to all

This site is great. Thank you so much for all your input.

Here's one last question:

Could you use the tankless coil (with a circ) for the piping to/from the indirect tank? Or would you have to add "external" piping for the indirect?

Thanks,

Tom

Lurkin' Murkin'

The tankless coil in the boiler usually has a lot of pressure drop, and since it's been used for 10 years, probably scale or other coatings that decrease it's heat transfer effectiveness. Best to use the same boiler water that the space heating zones utilize. The reasons given above, for using at least a dedicated DHW zone pump, are very true. You may get away with all zone valves, but there is a bigger chance of a problem in all around satisfactory operation. Standard zone valves also have a lot of pressure drop (there is a "CV" factor you have to consider), and indirects that have an internal coil have pressure drop that is a factor. You need the best flow to the tank - that means a dedicated pump of adequate performance and the piping to the tank from the boiler should be at least 1" diameter for residential sized tanks.

Bob Bona_4

abandon

the coil (don't plug it) and bring the hot/cold to the indirect. The indirect will have it's supply and return connections to the boiler.

Don't forget the best part..turn down the low limit on the boiler aquastat as far as it will go-you don't need to maintain 160+ anymore and you will begin to save fuel. The indirect will run as needed.

Tom S.

that was

going to be my next question - do you plug an abandoned coil or leave it open to the atmosphere. Now that is answered as well.

Do you see this as a big job or a small one? I'm not looking for a price here, just trying to get a relative feel for what I'm in for. 1/2 day job if all goes as planned?

Thanks again to all.

Tom

John White

Taco Zoning Circ

I think it would be appropriate to consider a Taco Priority Zoning Circ for this application. Wouldn't need to install a whole panel.
I'm no engineer, but this feels right to me.
Am I correct???
Help???...
JW

brucewo1b

Johnny White

It would work and is a great product, I just love the after effects of a clean looking install with the Taco ZVRC, makes the wiring simple and the diagnostics in the future a breeze well worth the price. Now if he had a Zone valve control that couldn't handle an extra zone on priority and just needed a circ to run the indirect I would agree.

John White

Zoning Circ

Bruce,
Thanks, guess I didn't get that part. Just a salesman, you know.
Man, I love the wall!!!
jw

Joe Mattiello

Hi Tom
I was reading your inquiry about adding another zone to the existing system. Apparently, you have 3 zones with zone valves and a tank-less coil for DHW. Adding an indirect water heater, and running the boiler as cold start is a great idea. May I recommend the ZVC-404 with priority to facilitate the wiring, diagnostic lights for troubleshooting, and dry contacts that work with the priority zone, for running a circulator for the indirect water heater? Additionally, you have the option to prioritize the DHW, so if the boiler is undersized because of the additional load you can temporarily interrupt the heat zones, until the DHW is satisfied. This should relax your mind about exceeding the capacity of the boiler, by adding the DHW, and have you spend more time thinking about buying the house that you love. See attached for instruction information.

Joe Mattiello

Tom S.

Thanks Joe..

I am getting ahead of myself with this house (that I don't own yet)...so much so that I've already poked around the Taco site and read the 404 manual! Thanks for attaching it here as well.

Looks like the right fit and everything about it makes sense. If we buy the house, it'll be on my list of improvements to be done sooner than later.

I appreciate all the really helpful replies from all the wallies.

Tom

Lurkin' Murkin'

Joe - the priority zone #4 can be wired to a zone valve or a circulator, according to the instructions. But it looks like the control only provides 24 volts, normally for zone valves. What additional components and wiring diagram are needed for the DHW zone circulator? Thanks!

Tom S.

Not that I pretend to be able to read this wiring diagram, but a more updated wiring sheet on the taco site (I think) shows 120v output for circs.

See it here:

Taco ZVC404 pdf file

Of course, I might not know what I'm looking at either...

Tom

Unknown

Johnny

For priority when installing an indirect to an existing boiler , we the Taco single zone relay with the extra NO-NC contacts . We just have to make sure we don't exceed the ratings of what's going through the NC side for the heating zones . Of course we always try to upsell a multi-zone relay with priority , but this setup works well also .