Wire up Taco Valve

I have a Taco SR-504 electronic control. Our system is set up with an buffer tank that is piped directly to the boiler and has a 0010 pump that supplies the boiler with water from the tank (primary loop)This primary zone trips the boiler via a connection to the T-T circuit on the boiler.

We then have a supply manifold that comes off the buffer tank and 4 007 pumps come off the manifold and supply heat to our 4 different zones.

The SR-504 is wired so that when any one zone (007) calls for heat, the 0010 pump circulates water through the primary loop. That is a necessity as the supply and return manifolds take off from the same pipe in the primary loop, and if the 0010 pump does not circulate water through the primary loop, we can't get heated water into the supply manifold.

However, currently, each separate zone (007) can also cause the boiler to turn on through the SR-504. Thsi seems to be creating overlapping demand situations on the boiler.

I am trying to make a setup where the only thing that will turn on the boiler via the T-T connection is the aquastat on the buffer tank.

I would like to set up the system so that if any thermostat in the house calls for heat, its corresponding 007 pump as well as the 0010 primary pump will turn on.

But only when the temp of the buffer tank drops below the setting on its aquastat, will the boiler fire.

Is it possible to wire the SR-504 like this, or do I need a different electronic control?

Thank you.

 

Not shore I under stand you reading your post [I] under stand what you want to do
could you post photos that will help
William

 

ok now I think I see what you are saying let me ask you
how long have you lived there ?
is this a new install?
primary loop does it run around the whole house ?? or just the boiler?

did you have rad. and replaced them with bb.?
William

 

William,
We have lived here for several years. The boiler is a high efficiency unit that we added the 70 gal buffer tank to because it was overheating, shortcycling, etc.
The primary loop goes between the tank and boiler. On the return leg of the primary loop, the supply manifold and return manifold come off the primary loop via 2 closely spaced tees.
As I mentioned, the aquastat on the buffer tank is wired directly to the boiler, as is the 0010 pump.
The SR-504 is wired via its X-X enswitch also to T-T on boiler.

I would like the 0010 pump to run when either the buffer tank or any individual zone calls for heat. However, the only way I would like the boiler itself to fire is if the buffer tank aquastat calls for heat.

 

Dave ok things are clearing up
expanion tank is used for water expanding what you have is a 70 water holding tank am I right ? if so working on the wiring as we type it can be done
Just asking first
if the aqua stat on the tank does not call for heat and no heat is needed in house you doint want the boiler to come on at all??
1 What kind of boiler do you have ??
2 what kind of 7o gal water tank do you have???
3 all control makes and #s aqua states on boiler ,tank,also any other relays

How do you get your bath hot water??

William

 

Correct. It is a buffer or holding tank.
Boiler is Lochinvar EBN300
Tank is 70 gal Ergomax. It can be piped to give domestic hot water but is currently only used as buffer tank
If buffer tank or any separAte zone does not call for heat, boiler does not run (cold start).
The only aquastat is the integral one on Ergomax tank.
Currently we get domestic hot water via Phase III indirect as separate zone.
We have total of 5 zones, all with separate 007 pumps (3 hydroair units, Phase III, and a radiant loop for master bath floor).

 

Dave, would it be possible for you to draw and scan a diagram of the piping?

With a buffer tank such as you have, it may be more understandable to call the two loops the BOILER loop, and the SPACE HEATING loop, rather than PRIMARY/SECONDARY...

Your tank has multiple ports, no? why then are your supply and return manifolds piped into the Does not the SUPPLY from the boiler come off the boiler, through the boiler pump, into a port on the Ergomax, then another port on the Ergomax return to the boiler?

And on the space heating side, does not yet ANOTHER port on the Ergomax go to your supply manifold, and still yet another port take water from the return manifold?

In other words, you are using FOUR ports on the Ergomax, correct?

 

no. There were only 2 ports on Ergomax. It is a few years old. So there is a 0010 pump that pumps from Ergonax into the boiler. Then another pipe carries the heated water from boiler back to Ergomax. Off the pipe that carries water from Ergomax to boiler, there are 2 tees right next to each other. One is a supply manifold with all 0007 pumps. The other is the returns from the heating zones. This was due to the fact that we had to retrofit Ergomax into system.
That is also why 0010 pump must run when any zone calls for heat

 

Dave how do you have this wired ?? ter 1 goes to ? on what aqua stat on boiler ,heater and 504 as well as oo7 amd 00100 pump
william

 

Each separate heating zone thermostat is wired into the SR-504 where the thermostat inputs go. The Phase III aquastat is also wired into the SR-504 as a thermostat input.

Then, below the relays on the SR-504, each zone pump (007) is wired to come on when the corresponding T-stat calls for heat.

The low voltage from the SR-504 goes via the X-X endswitch to T-T on the boiler, and the 0010 pump is wired into the boiler circuitry.

So when any zone calls for heat, the 0010 starts also, and the boiler comes on if temp is low enough.

I used to have the aquastat for the Ergomax tank also wired to T-T on boiler so if tank called for heat, boiler and 0010 would start. I have disconnected aquastat from Ergomax because in cold weather, that tank always stays hot.
I just want to decrease the # of times boiler comes on (# of separate zones calling for heat and potentially overlapping).

 

Dave, let me restate just to be sure I understand. A diagram would make this so much easier...

Supply from boiler, straight into tank.

Return to boiler through 010 pump, from tank

On that return line, you have a pair of closely spaced tees, which are connected to the supply and return manifolds.

Questions:

On which side of the 010 pump, suction or discharge, are the CSTs?

Are there check valves on any/all of the pumps?

How much re-piping, if any, do you want to do?

Here's my thoughts... and they might be all wrong, but just thinking out loud... I can draw a diagram if it's not clear...

On return line from tank to boiler:

TANK / SUPPLY MANIFOLD TEE / 010 PUMP / CHECK VALVE / BOILER

On supply line from boiler to tank:

BOILER / RETURN MANIFOLD / TANK

Check valves on all the supply manifold zones.

NOTHING connected to the XX terms on the 504

ERGO a'stat ONLY firing the boiler.

Here's how I'm envisioning this might work...

Zone calls for heat, tank is hot, no input from boiler needed. Zone draws hot water from tank, and returns cool water to tank. 010 does not need to run, if tank is hot enough, boiler does not need to fire. Check valve after 010 prevents flow into/out of boiler. Only flow is from hot tank to space heating.

Tank cools, boiler fires to warm up tank via signal from tank a'stat.

You could put ODR on boiler to adjust tank temp versus outdoor.

Like I said, thinking out loud, maybe flawed... food for thought/discussion.

 

Sketch of my previous idea:

 

Thanks very much for the diagram. It's actually pretty close to what we have now. Just move the supply manifold so that it is right next to the return manifold and put a check valve where you show the supply manifold, and you have our system.
I hate to have more repiping done, as with the glycol, it is messy and expensive. I also don't mind if the 0010 runs whenever any zone is on because the boiler is a direct vent and well insulated and water temp doesn't seem to drop at all when water is flowing through heat exchanger with boiler off.

After reading your last post, it gave me an idea:
What if:

1. We attach wires from aquastat on Ergomax to extra thermostat input on SR-506 that is currently not being used.

2. move 0010 pump wiring up to SR-506 and wire into ZR terminal on SR-506. That would mean that when any zone, including Ergomax calls for heat, 0010 will come on, thus circulating water in tank/boiler loop.

3.Run another wire from Ergomax aquastat and put that on T-T at boiler. (disconnect X-X from SR 506).


This would hopefully accomplish the following....when any zone, including Ergomax, calls for heat, 0010 will run with the corresponding zone (007) calling for heat.
Only a drop in temp of Ergomax will actually cause boiler to fire.

Does this all make sense? And thanks again for the diagram and advice.

 

Dave... you've got a 504 (originally stated)? or a 506 (now stated)?

What aquastat is on the boiler?

I don't think you want to wire the TT inputs on the 506 in parallel with the TT inputs on the aquastat because both of those inputs are powered by separate transformers... don't think that will work.

I'm going to look at this a little closer later on... I don't see the advantage of the buffer tank the way it's piped. In other words, how the closely spaced tees on the primary loop are going to draw down the BTUs from the buffer... but maybe when I redraw it, and 'become the water' it will make sense.

Which manifold is on which side? In other words, is the supply manifold on the tank side, or the boiler side?

Is the supply from the boiler piped to the top of the tank or the bottom?

Your first descriptions sounded as though the closely spaced tees are on the RETURN LEG from the tank to the boiler, in between the 010 and the tank. But your last message sound more like the closely spaced tees are on the SUPPLY side... please clarify.

 

Dave, another idea...

If all you want to do is prevent the boiler from firing until the Ergomax is cool enough, why not leave everything the way it is, EXCEPT:

Wire the Ergomax a'stat IN SERIES with the High limit control on the boiler...

This would allow all the pumps to run now the way they are, which is what you want, but it will prevent the burner from firing unless the Ergo's a'stat is NOT satisfied... this is presuming that you have a SPDT aquastat with adjustable DIFF...

What a'stat is on the ERGO?

Did you say that one of the zones was an indirect water heater? If so, that should be piped directly to the boiler I think, and on a priority circuit. I wouldn't try to use the buffer tank to run the indirect.

 

That could work....the aquastat is made by Thermtrol. I don't think it has an adjustable differential. But I don't think it would matter. Do you? I know it is closed until it reaches temp and then opens.

 

I would want the adjustable diff, because I would want to set it to a pretty wide setting so that you could take advantage of the buffer tank. If it has a narrow diff, there is no point or advantage to the buffer because your burner would fire before you were able to draw the BTUs out of the tank.

You wouldn't want the boiler firing to high limit, and then have the boiler fire again a few minutes later on a 10 degree diff, for example.

 

I also have something wired through the high limit called a Heat Manager that I think acts as a high differential. It monitors the drop in temp of the water coming out of the Ergomax and does not allow the boiler to come on until it sees a substantial rate of drop.
I would just wire the aquastat in series with that, I guess.
Here is the website: Residential Boiler Controls | Beckett HeatManager

 

Yeah, 'regulars' here know how I feel about the heat mangler...
Let's just say that I don't have a lot of faith that it [the heat mangler] is gonna do what you want it to do...

Bottom line is that the way the system is piped, you won't get the full advantage of the buffer tank, IMHO.

 

OK. I think you've convinced me to repipe return manifold as per your diagram. As I said, my system looks like your srawing except return and supply manifolds are next to each other in pipe that goes from bottom of tank back to boiler.

With my system, I would move return manifold from where it is now (directly adjacent to supply manifold in your drawing and move it to the other pipe (that sends water from the boiler to the top of the tank).

The checkvalve that is in the boiler loop of my system is just downstream of where the return manifold would be repiped into the pipe that feeds water from boiler to top of tank.

Then each small zone pump (007) currently has an integrated check valve immediately downstream of each pump.

In a previous configuration, we had an issue with 0010 pump forcing 180 deg water throughout whole system, so I want to be sure that doesn't happen again. That is why we moved supply and return manifolds so they were next to each other.

 

Dave, I meant it when I said that the drawing might be JUNK, and I want you to be ABSOLUTELY SURE that it is the best solution for your application before you commit to doing it! I was kinda hoping that others... (rbeck, xiphias, who, TO, etc...) would chime in on this... so I've put 'buffer tank' in the title to try and 'bait' the hook... maybe we'll get a swordfish on the line!

Notice that the check valve in the boiler loop in my drawing is on the circulator pump (your 0010), and note the direction it is facing.

If I understand what you are describing, it sounds as though the check valve will be in the wrong place.

What I was thinking:

1. trying to NOT repipe any more than necessary, i.e. not to rip out and re-do the whole tham ding.

2. trying to use the BTUs that are stored in the tank to the best effect, and minimize boiler firings, and achieve efficient run times.

The way I've shown this, the individual zones have no choice but to pump water ONLY from the buffer, and back to the buffer, due to the check valve on the 0010.

The 0010 pump and boiler would ONLY fire when the tank cooled to it's setpoint, whether that is from an ODR unit, or an aquastat. If you use an aquastat, you absolutely DO want one with a wider differential. You want to be able to heat the tank up, and let it cool... use the BTUs that are stored. If you only have say a 10° diff on the tank aquastat, you might as well not have the tank at all, because you aren't USING the BTUs that are stored there.

This needs much more thought than I've given it before committing to it... so PLEASE, don't do it on my account!

 

There's another thing to consider...

Your indirect water heater.

I don't think you want that running off the buffer tank. I believe you want that running directly off the boiler. You want the boiler to fire up to high limit when the indirect calls, and devote all it's 'power' to recovering the tank. If you use ODR on the tank, that water may not be hot enough to give proper recovery time on the indirect.

So, like I said, there's more to think about. Don't make any changes yet!

 

Dave, does this drawing represent your system 'as built' ?

 

Yes. Pretty much that is the schematic

 

This is a common way to pipe a buffer tank:

About Boiler Buddy

The setup as drawn ain't very efficient, esp for DHW.

 

How about the drawing that NJ Trooper had done last wseek? Does that look like it would work?

 

Dave, take a closer look at the boiler buddy diagrams. This is why I had asked early on how many ports were on your buffer tank. The newer Ergomax tanks seem to have a number, but you said that yours has only two.

What I was attempting to approach was a way to 'trick' the system into thinking that you had the multiple ports by placing the manifolds where I did, and using check valves to force the system to use the tank as it's heat 'store'.

The second boiler buddy drawing is what I was trying to get at with the indirect also... you want the BOILER to heat the indirect, not the buffer tank.

After looking at the drawing that is "pretty much" (what does that mean? is it, or isn't it? what's different?) how I think yours is set up, it probably _can_ be made to draw down the tank as-is, but would require some careful setup of the controls to work right. What I didn't like about it from the git go is that the boiler pump needs to run whenever there's a heat call... not that the extra electric is gonna kill your economy, it IS an extra electric use that may not be necessary.

 

The one that says it might be junk? It's junk.

 

EBN300? That is one honking big boiler, albeit it has two stages. You could do 6-7 normal houses with that on full fire.

Given the boiler is probably hugely oversized to the load, a properly set-up buffer tank would really help. Might also be that 70 gallons is too small. Depends on the load. What is the load, anyway?

You want the buffer between the boiler and the load. Presently, it's not.

You want the indirect supply and return right next to the boiler, totally independent of the buffer. Presently, it's not.

Can't really think of a way to set this up without additional ports on the buffer, unless you make it a pumped buffer, which would require pump and control. Check out

The Glitch and The Fix - Radiant and Hydronics

This is not ideal (requires pump and control, thus more complex), but it would work much better than what you appear to have now.

 

Wow. I wish we had those diagrams when we were getting the Ergomax installed. We built the house in 2000, and the heating contractor wanted us to get this super high end whizz-bangy boiler that was high efficiency.

As you say, we could heat half our town with this thing. The plumbing sub, who unbeknownst to us, had never installed one of these, worked on it for months and months. We had incredible noise (flashing to steam, shortcycling, etc). The final strwa was when we had numerous failures of the boiler pump (0012). He had put this huge pump in to move water through boiler at high speed. It failed 3 times.

We did research and found the Ergomax tank. Unfortunately, at the time, it only had 2 ports. It was piped with supply manifold teed into one side and return into the other. Unfortunately, we started having water pushed through all zones at 180 degrees, so the Ergomax person recommended putting supply and return manifolds together as closely spaced tees.

I must say that it is quiet and dependable, so I hate to mess too much with piping. The Phase III is essentially unneeded because the Ergomax can heat our DHW on its own, though we have not piped it as such yet. Phase III recovers very quickly even in current setup.

I don't mind that the boiler pump (0010) has to run whenever a zone calls for heat, as I have watched the water temp with boiler off, and it doesn't cool down with water cirulating through it.

In the summer, we spend about $40 per month for DHW, which I don't think is bad.

My mani concern is that any zone can cause the boiler to fire. That is why I wanted to wire it as such to prevent overlapping demand....

Each individual zone, including Ergomax aquastat would be wired as separate thermostat input on SR506.

Only the Ergomax aquastat would be wired to TT on boiler (piggybacked from SR506 input).

The boiler pump (0010) would be wired into ZR and netral on SR506 so that it would run whenever any zone, including Ergomax calls for heat.

The endswitch on SR506 (XX) would not be wired to boiler, so only Ergomax aquastat could call for heat.

I had originally tried twire Ergomax aquastat in series with high limit on boiler as NJ Trooper had recommended, but Ergomax temp fell consistently to 140. We tend to keep it at 160.

By the way, Ergomax aquastat is TS-090S-C2 on page 33 of the following link
http://www.thermtrol.com/ThermtrolPD...20Lo%20Res.pdf

 

Sorry. Yes, actually it is exactly like that.

Although the indirect is not super efficient as piped, we only spend about $35-$40 per month on gas in the summer for DHW, which I think seems pretty reasonable. That is for 2 people with showers, laundry, dishes, etc. Also, some day, we will have the Ergomax piped for DHW as it has its own heat exchanger. Then Phase III will be obsolete.

Are there any ways you can see doing this without reworking the whole system?

 

Holy Carp! I never even looked at the boiler size! Whyinhell is that boiler so big? That's just nutz!

Don't hold back man! Look it over and tell us WHY it's junk.

Make sure that you note my caveats about the Indirect tank, and note that they are the same as yours... I didn't draw the tank where it belongs, but I texted it...

I maintain that with the proper controls, and the check valves in the proper places, that two port tank will come close to having the extra two ports as on the boiler buddy tank.

When a zone calls for heat, it will draw ONLY from the tank, and when the tank calls for heat, it will fire up the boiler. It looks to me that the FUNCTION would be nearly identical to a tank with 4 ports, but FORM may be different...

Yes, I said it might be junk, but don't dismiss it without telling us why.

I think you might be missing the point of having a buffer tank Dave... you WANT the buffer tank to swing the temp like that... think of the buffer as a BTU STORAGE tank. You fill it up, let it run down, fill it again, etc... if you want, or try, to KEEP the tank at 160, then what is the point of having the tank at all?

If you treated the gas tank in your car the same way you are treating your buffer tank, you would be putting a couple bucks in each day, rather than let it go to say 1/4 tank and then refilling...

BTW, I don't think $40 a month for DHW is very good at all... that's almost exactly what I pay per month to run my ELECTRIC 40 gall WH.

The reason that it's high, is because in the summer months when you don't have any reason to keep that big buffer tank warm, you are still doing so. Not only are you heating the indirect, you are ALSO heating the tank... then, the indirect has to actually WAIT for the big tank to get hot before it receives any heat... no point in that!

If you had the indirect piped directly off the boiler, then ONLY the indirect would need to be heated, and it would quickly have the benefit of full temp water heating it up.

I would not move so fast to replace the Phase III with the 'tankless' coil in the Ergomax either... the indirect gives you STORAGE, while the Ergomax does not. The domestic coil in the Ergo is nothing more than a larger version of a tankless domestic coil in a boiler... exactly the same principle. Small volume of domestic HW in a coil inside the large tank, bathed in hot water.

 

Ya know, I hesitate to say this, but the real solution to your dilemna is to get rid of the behemoth and install a properly sized boiler. Anything else is a waste of time.