Timer for use wt Tekmar

Unknown

a global reset curve is unlikely to be accurate for every room in the house.

I suppose you could take the stance that if you're unoccupied, room temperature precision isn't that important. That's valid. However, since tN4 would also bring in zone synchronization for a 10 zone system here during both occupied and unoccupied modes, it would seem to be a pretty good choice IMHO.

this doesn't sound like an existing system and doing a zone only upgrade of tn4 compared to all programmable thermostats, you're only talking about $500 maybe. On a ten zone system, $500 isn't much, and the zone synchronization should be a feature worth buying at that price. Of course once you're there, it's only a few hundred more to a fully indoor feedback system which is top of the line.

but you and andrew have good points, if you don't care that the setback temp may vary around the house, doing it on water temp is viable, cheap and easy. tn4 isn't the only game in town for sure... it's just the only game that makes sense for ten zone mod/con systems ;)

Wayco Wayne_2

I need at timer

to provide set back for a Tek mar 361 control. what do you use for this application?

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CC.Rob_4

simple and effective

HO here. This is a trick I learned here on the Wall. Works great.

I use a LUX500 thermostat as a timer for my tekmar 260. To short 11/12 (UNOCC/setback mode), set the LUX temperature to 90F (or 85, or whatever the highest setting is; I forget). The LUX generates a continuous "call for heat" that shorts 11/12. When you want to open 11/12 (OCC mode), set the LUX temp for the lowest setting (45 or 50, IIRC).

Because the LUX is 5/2 programmable (and 4 settings per day), it should meet most normal setback requirements.

The only caveat is to make sure that wherever you place the thermostat (mine's next to the tekmar) it won't see 85-90F or 45F). My basement is always within 5F of 64F, so not an issue.

Unknown

what are you using for room control wayne? thermostats, or just the indoor sensor?

Wayco Wayne_2

The rooms all have tstats

that run the Zone valves that have end swtches that go to the current VSI control to initiate heat. I'm installing the 361 so I can shift the curve down using the UNocc set of contacts. I need to shift back 2 times on work days and once at night on weekends. Should be simple right?

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Unknown

what's the deal, you don't like programmable thermostats? having the curve be off during unocc mod isn't really that big of a deal, right?

or are you just trying to keep programming down? If so, you could use tn4 thermostats, say 537s with one 542 master programmable thermostat.

Wayco Wayne_2

There are

about 10 thermostats. To install 10 thermostats would be too costly, not to mention a PITA to program and maintain all of them for the HO. One central turn back is mo betta. WW

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Unknown

gotcha. well I'd do 9 537 thermostats (members) with a 542 (programmable master with 4 events per day). 335 zone manager. maybe a 480 user switch if you want one button setback as well. The 542 will make all members set back and recover with it.

would also give you zone synchronization, which is pretty cool for keeping cycling down.

this is probably less expensive than 10 programmable thermostats, but maybe not.

ALH_4

Timer

That sure seems like a complicated way to accomplish global setback. I'd just hook up a Tekmar 032 timer. If you need to set back each zone differently, the tN4 route may be best.

Unknown

but on a 361, that will only set back the water temperature, correct? Not the room temps. So you'll end up with ten zones of constant demand running at some arbitrary reset curve.

[Deleted User]

Grasslin,

now Intermatic, DIGI 20A-24. 24 Hr & 7 Day. 100 hours backup. 24V Input.

Use them on all our Tekmars.

Unknown

Arbitrary? Why does this curve have to be arbitrary? If the zones are well balanced and the radiation is sized properly this global reset curve could be quite accurate. I have Viessmann ODR only systems running with no indoor feedback that maintain nice even room temps .

I wonder how important accurate zone by zone setback really is. If you are sleeping, does it really mater if the kitchen is a few degrees different from the bedroom. I say find a setback curve that kicks all zones into constant circulation and provides just enough heat to maintain desired min setback temp.

Wouldn't a global setback that lowers circulating temperatures be more efficient than 10 un-synchronized zones running off separate setback thermostats on a higher than required curve? Tn4 or Honeywell AQ2000 would be the best way to do this but I think you may be exaggerating the insignificance of the price difference. One nice feature of the aq2000 is that it works with existing two wire cable. If the tn4 upgrade means rewiring 10 stats this alone would be a significant cost.

ALH_4

Global Setback

My experience with global setback is similar. I have seen Vitodens boiler started up before the thermostats were installed that held the indoor temperature surprisingly accurately. I have also seen systems that ran exclusively on the outdoor reset curve with and without indoor feedback with "tweaks" made by controlling flow to the zones. If you zone with thermostatic valves, all you need is outdoor reset and global setback.

I don't know exactly how much difference it would make, probably a small one, but lowering the system temperature during setback should help the efficiency of a condensing boiler somewhat in addition to the reduced heat loss due to the lowered room temperatures that programmable thermostats would provide.

Unknown

tn4

Rob, I'm a bit confused, tn4 room sensors need a zone manager and a zone manager needs a reset control, right? how is indoor feedback an add on? I thought this was part of the whole package. What am i missing?

As far as zone synchronization I was wondering about tweaks like requiring smaller zones to run along with other zones, avoiding small loads that might cause cycling. In it's out of the box state the system is striving to stagger demands from various zones to achieve a more constant load, correct? I haven't looked at the literature in a while, but I seem to remember some options for tying zones together, Running small loads together when possible might be advantageous,especially in highly (micro) zoned systems like the one in question, have you ever played with these settings?

Unknown

you can do tn4 zoning only without a reset control head. This nets you zone synchronization and the benefits of the network as far as one thermostat programmability, user switch is concerned, but sacrifices indoor reset (which you could add later, if desired). Naturally, adding a head is generally a worthy upgrade at this point, but sometimes that isn't possible or desirable for a variety of reasons, such as you're using a boiler that is not tn4 compatible.

if you allow the tn4 system to do its thing, I think all zones synchronize. I believe the typical action is every 15 minutes, ALL zones that should need heat in the next 15 minutes fire together, and just drop out as they receive the "burst" of heat they need for that 15 minutes.

Staggered demands I think might have been standard in the old tekmar systems, but tn4 I believe is synchronized standard. Or at least it's standard in our typical setup, my partner is the tekmar guru but I think I have that all right at least.