taco schematic metaphysics

archibald tuttle

>http://www.functionaldevices.com/

Thanks Dave. Nice pics. I have occasionally seen these relays in the past but forgot about them as a possible solution for compact effectiveness as well as cost effectiveness (although I maintain the most effective solution would be for TACO to come across with an installer addressable relay exploiting the full capabilities of the components they already employ in their relays by redesigning the circuity board). Where do you buy your functional device relays? The inductive relays are really cool also although the web site does not have either suggested retail or trade pricing so I'm assuming I have to go through a distributor either locally or over the web.

Who do you use?

Brian

archibald tuttle

taco schematic metaphysics

So TACO has all of these diagrams for their 50x exp series relays and none of them show you what the relay does, they only presume ahead of time what you will do with the relay and tell you to hook up various wires to their magic box which they are unwilling to say what is inside. Further they won't even give those internal schematic diagrams to their technical help people. Supposedly its proprietary. This is ridiculous. I'm not asking for the programming algorithms for the TACO labeled tekmar set back and variable speed ciruclator options, I am just looking for an extra set of dry contacts to trip another relay in addition to the boiler rather than sorting phases from the two relays and praying by putting the t t's in parallel to run two relays.

What I am wondering is if the expansion connections that normally signal from a slave to master setup to trip the boiler are independent dry contacts or in parallell with the x x boiler terminals.

I could jump the whole mess out by using a PC 702 instead of a PC 700 even though I have a single boiler because that gives boiler contacts on the 702 and leaves the x x terminals on the 503 exp available although if you use the 702 I don't know if the x x terminals reflect loop demand or temperature demand on the boiler. The 700 obviously returns the signal since you hook the boiler up the x x but I don't know if the 702 does. I have put a few in but I wasn't trying to get an extra end switch for anything on those installations so I didn't think to test whether loop demand or temperature demand from the setback controller calls the x x in that circumstand.

The only option TACO offered was to install a 501 relay and by pulling a jumper from the circulator contact I would end up with two end swithes or 'dry switches' but that means adding another relay in line, yhet another relay to treip a realy.

In this case I'm looking for a dry switch. If I were just looking for a loop demand signal, I guess I could grab a 120 signal off of ZC but that will not reflect the setback controller call so I can't use it just to run the boiler - assuming I could figure out the load rating for the circulator relay and it could take the burner motor.

Now, with a tester and an hour or so on the bench I could probably reason some of this out, however i'm hoping someone might have done this before and could help with this. Anyway, if anyone has gone before me on this and sussed out a schematic of the 50x exp controls or got any suggestions for obtaining one more dry switch coordinated with boiler temperature demand I would appreciate their thoughts.

Brian

Merry Christmas, Happy Channukah, etc.

Tom M.

Would this work?

You say that you want to pull in another relay in addition to the boiler. Can you get that relay with an extra set of contacts? Then x-x could pull only that relay in and the extra contacts could pull the boiler in.

Tom M.

archibald tuttle

Tom,
Thanks for the suggestion. Problem is I'm using a different setback strategy for each relay so I'm using the signal to turn off another relay rather than on. actually my idea was to stack two exp relays and turn the other one 'off' by calling the priority circuit. Actually it would be more straightforward in some ways of exps had a NC contact on the dry switch (in other words the dry switch was SPDT). Ideally DPDT would be great but begging TACO for even one more contact seems futile as I have been an advocate of their adding a dry switch, i.e. one more contact, to their zone valves for years and they ain't interested.

Anyway, my stack strategy would theoretically fire the boiler at full temp, but I have a downline Tekmar 256 setback unit so the primary exp with a TACO 700 (i.e., another tekmar control) set up for baseboard rather than floor radiant temps will actually be controlling boiler temp.

At the same time, when I am running the boiler hot for the baseboard, I will use that priority circuit on the second relay to fire a circulator manifolded on the return to send return water to an indirect that is running radiant floors. Using the priority circuity will turn off the traditional feed circulator which would normally perform the function of heating that indirect in accordance with the dictates of the 256.

My idea is to try to keep the return around 140 regardless of the feed temp. It is kind of my cost saving attempt to duplicate some of the more sophisticated functions of a Tekmar controller without paying 800 bucks for one, plus I don't know if even the new Tekmar controllers would allow me to tell it to run one circulator for a particular loop if the boiler feed temp is high and another if the boiler feed is cooler.

MAybe someday the Zigby thing will be realistic and I can just take a bunch of sensors and program a PC to do all this just the way I want it. It is frustrating that you can buy a PC for a few hundred dollars but you have to pay two to three times as much for a controller which is a hell of a lot better than a dumb relay but the programming is only addressable to a modest extent.

For instance, I will eventually have a solar loop also feeding the floors in this system and I would want to be able to tell the boiler to wait if I anticipate some solar gain. Might do this with a temp. sensor somewhere on the collector as I don't know of readily available photosensors that would be able to tell the difference between sun and incident light, but there isn't any way I know of to tell the Tekmar controller what to do with that kind of input.

My early kind of 'cheat the engineers' plan would be to use an interstage delay, but none that I have found allow me to set that delay to say 6 or 8 hours hours if there is some temp. rise coming from the 'lead' source, i.e. the solar. They are all based on single digit count of minutes for lead, lag separation. The engineers have presupposed how we're going to use these.

I appreciate the work that has gone into the various automated proportioning functions that these controls can provide, but I think that there are few reasons other than hard headedness (I've got plenty of my own) not to allow some of these setpoints that are addressable or overrideable to have a much greater range of adjustment. Their sensors can tell time and temp over a wide range so it is strictly their programming preferences that create these roadblocks. It would be essentially cost free to open up these parameters other than they decided not to and have ROMed these constraints into their current product line.

Why is the interstage differential limited to 4 minutes and/or why isn't it addressable as a matter of delta T between the setpoint and feed temperatures. Thus you could delay the boiler stage as long as the solar feed didn't fall say more than 20 degrees below the setpoint.

The stack of controllers that I have put together to do all this is running up towards the $700 mark so a Tekmar controller begins to look not silly costwise, but it still is not as addressable as I would like and the stuff I am putting together is less 'black box' oriented. It is kind of like physically programming using relays as crude digital devices.

I went to a seminar on the new Tekmar stuff, and their idea of constant data communication between heated space and controllers is interesting but requires yet more investment in their proprietary thermostats. Maybe if they sell a lot of this stuff it will eventually come down in price somewhat (this is actually most likely if they get a serious competitor for obvious reasons). And still, Tekmar tends to remain in control of what gets done with all these setpoints giving a limited range or options to the installer.


A novella by
Brian

Joe Mattiello_2

Taco zone control wiring guide

Brian
I have read all of your correspondence, and the only Taco issue I have uncovered is the fact you need an additional contact for a primary pump, when using a SR 50X-exp, when interfaced with an outdoor reset control PC700-2. Taco, has for reference the Taco zonecontrol wiring guide, and many alternative wiring schematics that will help you with your system design. For your reference I have attached the Zone control wiring guide. Please refer to page 15 for a SR board interfaced with a PC702 two boiler reset control, where we show a primary pump off ZR terminal and using the reset feature of the PC702. Simply turn off the 2nd boiler staging and you are done. I'm available for question Monday thru Friday.

Joe Mattiello
Technical Support Technician
Tel. 401-942-8000 X 484
Fax. 401-942-2360
joemat@taco-hvac.com

archibald tuttle

taco issue

Joe,

The TACO issue that you are not addressing is that I can't get a schematic that tells me what this control does. All I can get is diagrams of various recommended implementations and then I have to reverse engineer what is happening in the control. I have looked at them all. If I was simply trying to start a primary pump in additiona to trip the boiler, I would have no problem but that is not all I'm trying to do.

If you guys have some competitor who wants to knock off your control they can have an engineer do that in a couple of days, maybe a couple of hours. So why do you prevent your customers from having a schematic of the control or simple theory of ops so I can readily establish what I can do with it.

Lacking this, I pulled apart a 506 exp and spent some time holding the circuit board up to the light so I can see both resist layers at once and I have now developed some more TACO issues.

When you made the 501 relay into a mulitiple design you took the used same DPDT relay that provides two independent switches including NC terminals on a 501 and you threw away essentially 3 of the 4 'logic' terminals making a DPDT into a SPST.

The two switches in each relay appear to be fused together in parallel. I thought perhaps the reason I didn't have access to an independent end switch for each zone is that you were using the second switch on each relay as calls to the master relay. No, it looks like the 24 V thermostat call from each zone is transmitted through a diode to the master relay so you don't get feedback from one zone to start another but each zone calls the master using thermostat closure and not relay closure.

So the end switch or dry switch for each zone is wasted and there aren't even any attachments to the board of the NC terminals on these individual relays. Even keeping with the idea that the master relay is going to run boiler events, they don't give even give us a master NC terminal. It looks like although I have to power this up and test it that there is one NC connection to the priority relay that delivers a signal that the priorty relay is not called. I haven't been able to focus long enough to figure out if that is dry signal, 24V or 120 V but I can make sense of it in terms of theory of ops I am deriving and I could grab the NC signal at the expansion terminals, however I am not looking for NC on the priority, but NC on the master demand for any of circuits including priority. (ideally I'd be able to choose which circuits, then I could keep all the circuits in this instead of running one independently, but I'd settle for a master NC signal).

My particular problem isn't just running a primary pump, it is also to turn off one circuit when others are calling. The converse of priority style response in which multiple circuits are turned off when the priority calls, I am trying to make one circuit an anti-priority circuit so it doesn't run when any other circuit calls.

As it stands I will have to stack two 501 relays to get the job done and use the 120 call to ZR which also fires the 120 volt coil on the master circulator relay (separate master relay) to power a 501 serving just as an auxilary relay. When no zone is calling, e.g. no 120 to ZR, there will be no 120 going to the intermediary 501 which runs a circulator feeding radiant storage off the return. The NC contacts will be made through a Tekmar 256 to the T T of another 501 that runs a traditional feed circulator for this indirect storage so if the return heat off the other zones isn't enough to keep up the indirect tank will get traditional circulation.

I have no problem if TACO techs don't want to make specific recommendations regarding atraditional which your engineers did not consider in their designs for liability or warranty issues, but I am indignant that you don't just publish a schematic of the control and I can figure out what loads I can appropriately apply to what terminals and so forth. Secondarily, it is unfortunate that in the thoughtful creation of multiple zone relays some of the flexibility of the single zone relays has been written out of the equation unnecessarily.

This is harder to solve than the reverse engineering because once a design is locked in you would have significant costs to change it. Maybe if there were a lot of extra terminals some folks who want the most straightforward applications could more easily make a mistake hooking things up and I can see an argument for not overloading the thing with terminals (an argument to which I would not subscribe, but I can acknowledge it).

But it is disappointing that there isn't even a more straightforward extra dry switch (better yet say an extra dry swith with a little dip switch by each relay so that you can determine which zones call this extra switch), as well as that there is no longer any access to any NC signal.

Opening up your standard is not going to make other TACO products more or less attractive. It is not as if offering the schematic means I am less likely to buy a TACO circulator, for instance. Any 120 circulator hooks up regardless of whether or not I have a schematic. It is highly unlikely that you'll loose business for you plug in cards or setback controllers simply by letting us know what the pine connections do (as opposed to the programming that decides what these add ons tell those pin connections).

If you want to close your marketing standard,you could make the circulator connections plugs instead of terminals and you could sell different length plug in connections for circulators similar to the plug in connection for the 700 and 702. Then folks who buy your relays would have to buy your circulators unless they felt like wiring plugs onto a competitors. And there is a certain plug and play (forgive the pun) conenience to the idea of a relay that circulators just plug into and then ther is a plug on the circulator end as well. You could have clips or a screw to insure they don't get knocked loose so you don't provide an source of accidental zone failure and you are off to the races (and the bank).

That said, if I find your designs that tend to force customers in house stulifying, I will avoid them. Your refusal to provide an independent end switch on your zone valves is one of the principle reasons I use circulators and not zone valves. And your multiple zone valve relays are of course attuned to this silly design so I don't buy them either.

And finally, I stated several specific TACO question which your techs don't know the answer to. What happens to the x x terminals on an exp control when you are running a 702 multi-stage controller. It is still cheaper in my application to run a 700 and add an additional 501 (the 702 street price is about $80 more than the $700 and the 501 is a little over 30 bucks) but if the x x are available and simply show system demand that would be a more elegant way of doing what I'm trying to do with less boxes on the wall, so I might do it that way if anybody would own up.

Also, is it a diode clipped 24 volt signal that is sent via the expansion terminals from the slave to the master. It looks like if I'm clever I could grab the number 2 expansion terminal and common from the 24 v output terminals and disable the transformer on my 501 and run its relay from the 506 and that way I could also eliminate the intermediary 501.

sequal to a novella
by Brian

allenh

I would like to have a controller

that would sample water from various zones say every 20 minutes when its below freezing outside. And if comes back at say 50 degrees than run that zone for say 5 minutes. This would keep all zones from freezing should people shut them off.

I would also like a way to control return temp on the boiler to say 140 or 150 for days above freezing. And have it a tad higher on days below freezing.

We pay heating costs for tenants and sometimes we see whoppers of bills!


I believe that a flash memory might be one option to do this.

Dave Stroman

Brian, I use a lot of Taco boxes and need extra contacts from time to time. I use RIB relay boxes. http://www.functionaldevices.com/
I can get a relay that does the same thing that a SR501 does for about $12. You just have to supply it with an external power source. They fit nicely in the knock outs in the Taco box.

Dave in Denver

archibald tuttle

> that would sample water from various zones say

> every 20 minutes when its below freezing outside.

> And if comes back at say 50 degrees than run that

> zone for say 5 minutes. This would keep all zones

> from freezing should people shut them off.

>

> I

> would also like a way to control return temp on

> the boiler to say 140 or 150 for days above

> freezing. And have it a tad higher on days below

> freezing.

>

> We pay heating costs for tenants and

> sometimes we see whoppers of bills!

>

> I

> believe that a flash memory might be one option

> to do this.

archibald tuttle

I would like to have a controller...


> that would sample water from various zones say

> every 20 minutes when its below freezing outside.

> And if comes back at say 50 degrees than run that

> zone for say 5 minutes. This would keep all zones

> from freezing should people shut them off.


Allen,

I agree wholeheartedly. There are several solutions to this all of which should be readily implementable on one of expansion card connections on the exp relay. TACO already makes a pump exercise card, however the purpose of this card is largely to start the pumps during off season so they aren't frozen up (i.e. stuck, not literally frozen) when the next heating season arrives). This is a quality response to an identifiable deficiency in hydronic heating systems.

However, replacing a pump is cheap and easy. Replacing frozen baseboard and the damage resulting from the thaw and leak that often happens before the homeowner really understands whats going on, or before the absent homeowner returns from wherever is far more expensive and this kind of damage often occurs in the rump of the heating system rather than a frozen pump which will show itself early in the heating season when freezing is not a problem and only mild discomfort results.

Therefore, while frozen pumps may be a problem that TACO identifies as reflecting poorly on them so they are trying to do something about, for system installers, operators and homeowners, and anti-freeze card would be a much better bet.

With a setback controller you already have an indicator of outdoor temperature. While this does not measure temperature of the hydronic media in an at rest loop, it is a reasonable surrogate and all they need to do is sample the outdoor temperature and adjust their exercise feature accordingly. So once a day exercise during the summer might need to be once an hour when it is zero out.

Doing this would bring at least interior temperature water into these loops without even starting the boiler. IF some other circuit happens to be calling it would actually bring hot water but a 3 or 5 minute circulating cycle while another loop is running is not going to significantly alter energy use and is going to prevent freeze up.

For that matter, when I have unattended houses, I lock all the circulators constant on and then just start the boiler from one thermostate set for say 50 degrees to maintain minimal heat but constantly circulating water. Again, TACO's failure to take advantage of the DPDT relays in their ganged relays makes this a manual job whereas if one side of the relay fired the heat and the other side fired the circulator you could more easily chose constant circulation in that type of circumstance. I have to pull the hots and gang the to the line feed in order to accomplish this.

> I

> would also like a way to control return temp on

> the boiler to say 140 or 150 for days above

> freezing. And have it a tad higher on days below

> freezing.

>

> We pay heating costs for tenants and

> sometimes we see whoppers of bills!

>

> I

> believe that a flash memory might be one option

> to do this.




There are reset controls that plug into the TACO exp relays to do this. The PC 700 for single stage application and the PC 702 for multistage. You can use either feed or return temperatures as a surrogate and they are more sophisticated than you are even considering. They regulate the hydronic media temperature on a sliding scale compared to outdoor temperature. The TACO implementation is very cost effective and simple top install. Since I have been bashing the limitations of numerous of their designs I should give them credit for this innovation (the control is actually made by Tekmar and I don't know who makes their EXP relays, but they are all marketed under the TACO brand name, are affordable and forward thinking in design except for all the caveats I have mentioned in this thread (plus any I have forgotten).

Dave Stroman

Brian, I use Burke Engineering as my local wholesaller for RIB controls. www.burkehvacr.com. They have several branches around the country.

Dave in Denver

brucewo1b

Brian The Taco Exercise card that can be used in Taco EXP controls can be set to 4 ins on every hour for freeze protection

archibald tuttle

Bruce,

thanks, I just ordered an exercise card and haven't actually had my hands on one yet, and I figured that you could backwards engineer a freeze protector out of it. Although my point is that there is no reason to have to set it that way. If the exp has a setpoint controller they could have set up up a way to poll the 700 or 702 for outdoor temperature so the control is smart enough to do its own antifreeze cycling. Then you can leave it set for offseason cycling instead of having to set it one way for the heating season and another way for the off season.

Brian