Vitodens 100 two zones or Tekmar 370

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Old 02-04-13, 11:19 AM
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Vitodens 100 two zones or Tekmar 370

I am considering replacing the boiler in our two zone system with a Vitodens 100 and wonder how it can be used in a two zone system or otherwise with the Tekmar 370 in place presently.
 
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Old 02-04-13, 11:30 AM
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You would do away with the tekmar I assume . The unit has its own ODR.
 
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Old 02-04-13, 12:05 PM
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How can I have two zones with the Vitodens 100?
 
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Old 02-04-13, 12:28 PM
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You have zone valves? You use two t stats. The boiler had ODR. The boiler will adjust temp based on outdoor temps.

I would take it to understand the tekmar you have now is ODR with a conventional boiler?
 
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Old 02-04-13, 12:48 PM
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Tekmar 370 is an integrated "house control"

http://tekmarcontrols.com/images/_li...e/370_d_06.pdf

I think you would be better off to turn the ODR on the vitoden off and keep the 370 wired as is.
 
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Old 02-04-13, 12:58 PM
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I am obviously not understanding.

Presently there is a conventional boiler, two zone valves and two thermostats connected to the Tekmar 370 but as there is only one thermostat connection on the Vitodens 100 I don't understand how it can differentiate between the two zones. All the diagrams I have found so far have been single zone or rely on an external boiler/DHW controller. How is the second thermostat connected and how is the second pump controlled separately?
 
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Old 02-04-13, 01:08 PM
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OK, that makes sense (I missed your post NJ).
 
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Old 02-04-13, 01:20 PM
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You can connect that tekmar to the boiler I believe with this open therm option. I would assume you get the best of both worlds?


http://www.viessmann.ca/etc/medialib...-Module_ii.pdf


there is only one thermostat connection on the Vitodens 100
The end switches of the zone valves would go to the TT at the boiler. So either zone will fire the boiler.



 
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Old 02-04-13, 01:22 PM
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I assume...(hate doing that) that you are using Tekmar RTU's to operate the 370.. If so then absolutely stay with the 370.
 
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Old 02-04-13, 01:33 PM
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I am using Tekmar RTUs and will continue to... through the module.

Thanks folks,

Jim
 
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Old 02-04-13, 04:52 PM
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Didn't have time at the 'day job' to get a good look at the boiler... but I'm rethinking now.

I think you might want to use the built in ODR and other controls in the Vito to control itself, they are tailored for it.

Do you know if it's possible to defeat the ODR in the Tekmar and simply use that as your 'zone control panel' to only send a heat demand signal to the Vito? (I haven't fully grokked the manual for that one yet either).

[later edit]

You haven't purchased the Vitodens yet, correct?

After quickly looking over both the Vito and the Tek, I'm not sure they will play well together. You might consider something else as a replacement.

How is your existing system piped?
 
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Old 02-04-13, 05:19 PM
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troop he can connect with that open therm option I linked to, no?
 
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Old 02-04-13, 05:53 PM
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I looked at that... but that looks like a 0-10VDC signal... I breezed over it quickly, so not sure.

It seems a waste of either one to try and hook the two together.

Why pay all that money for them fancy controls on the Vito only to disable them, why neuter the 370?

Somehow it just don't make sense to me. It would be like having a tug-o-war 'tween a Ferrari and a Lambo...
 
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Old 02-05-13, 06:06 AM
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I reached the same conclusion as NJ Trooper and have started a search for a boiler without ODR; in part because of Canadian prices. Paying a lot is one thing, paying a lot for something that will not be used is quite another. Presently the Tekmar just switches on the boiler which has two states; full blast and off. Is there such a thing as a boiler capable of modulation without ODR than can be managed by a 370?
 
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Old 02-05-13, 06:41 AM
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One of the reasons I asked about how your system is piped is because I wondered if a modulating boiler would even be of advantage to you. It may be not...

Whether or not a modulating/condensing boiler is of advantage would depend on what percentage of the heating system you can actually heat the home with boiler water temperatures BELOW about 130F or so.

If heating your home requires that you require boiler water temps higher than that for most of the season, the efficiency gains that are possible with a mod/com simply won't be there for you.

Once a mod/con is NOT condensing, it's efficiency returns to that of a conventional boiler.

So consider your needs carefully in order not to spend money that won't ever pay you back.

Explain your system and we can help.

How is it currently piped? Out of the boiler into the zones, and back again?

What type of heat emitters?

Do you have a 'feel' for the water temperatures that you normally need in order to heat your home?
 
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Old 02-05-13, 07:57 AM
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Explain your system and we can help. - NJ Trooper

The system consists of boiler (RayPak WT105), storage tank(see photo above) and two 800 sq ft zones (basement and floor above) using in-floor plastic pipes for areas 32' X 24'. It is managed by a Tekmar 370. The furnace heats the water and passes it to the storage tank. The tank in turn feeds the loops (four upstairs, two in the basement). I ran the pipes about 15 years ago and do not know their length, although I seem to recall the ones on each floor are equal length. (I thought there were four in the basement and then remembered the utility room floor - boiler location - is not heated.)

How is it currently piped? Out of the boiler into the zones, and back again? - NJ Trooper

There is a holding tank fed from the boiler by an independent pump, pumps for the zones and a pump to move the water from the tank to the loop feeding the zones. All water is returned from the floor pipes, measured by the 370 and hot water is added to bring it back up for recycling.

What type of heat emitters? - NJ Trooper

ASTM F876/F877 - is my best guess for your requirements from the information written on the pipes. Other information is Hauser ER 4407 UB 04980706. If none of this is correct please let me know and I will try again.

Do you have a 'feel' for the water temperatures that you normally need in order to heat your home? - NJ Trooper

The 370 is set for a heating curve of '2' and a maximum supply of '150'. Is that the answer to the question? If those are the numbers you require than I can add it does a great job.

I should also add the tank was an after-thought and not terribly desirable. If required, it will need to be replaced.
 

Last edited by jwwbrennan; 02-05-13 at 08:26 AM.
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Old 02-05-13, 10:17 AM
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(see photo above)
I don't see any photo links in any of the posts?

I would like to see more than one actually... how you have the 'buffer tank' piped in. If you do go to a mod/con boiler, you may be able to eliminate the buffer tank...

Since you have RADIANT floors, a mod/con boiler WILL be a good match.

I'll write a few more cents worth later this evening.
 
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Old 02-05-13, 12:53 PM
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The alleged photograph:

Name:  Boiler1.jpg
Views: 2318
Size:  44.6 KB

Please excuse the photographs, it is very tight. I can take detail shots if required.

I appreciate all this.

Thank you.
 
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Old 02-05-13, 02:04 PM
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Well IMO it would seem the tekmar cycles the boiler on and off to control temp right?

After looking at the pics, and since youwant to replace the boiler, I will say a mod con is best. I would rip it all out, tank and all.

The modcon will modulate down with low temps that you desire, and save you fuel.

Also save some electric. You will not need all those pumps..

The only thing I wonder is what your delta t is for your zones??? You said only two zones?
 
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Old 02-05-13, 03:15 PM
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The Tekmar controls the boiler with what appears to be a simple switch operation, although I can't say for sure. That is why I thought finding a boiler that could be controlled by a Tekmar would be simple.

'Ripping it all out' is a little elusive to me. I was hoping to lob off the boiler and the buffer tank while retaining the radiant floor parts and any required pumps to operate it.

The problem with installing a mod con is getting it to operate two zones. The present avenue of investigation is to find a mod con without ODR that can work with a 370. The Tekmar literature says "The supply water temperature to the zones is modulated based on both the outdoor temperature and indoor temperature feedback from each of the zones." As it is a controller without a boiler I supposed (saved me from presuming) it was able to convey that information to a boiler without ODR designed to work with such a control. I now realize it takes water at a predetermined temperature and modulates it only by mixing it with the return water.

Frankly, I have no idea why there are so many pumps but I addressed that by repeating to myself 'I am not a plumber, the plumber knows best'. I did the grunt work with a plumber. My single design contribution was asking to have the buffer tank added as it didn't make sense to fire up the boiler for every call.

It appears I am out of my depth in plumbing and will need to find some bucks.
 
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Old 02-05-13, 04:11 PM
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Jim, may I ask what the motivation is for replacing the boiler?

I doubt you will find a mod/con without ODR. Without an outdoor sensor, how would the boiler decide what temperature to target, and how much to modulate down?

Scrapping the 370 would not be an option for me. All your zone valves, RTUs, etc... all wired already.

If you scrapped the 370, you would probably want to replace it with another control panel, rather than go to the "rat's nest" wiring method... a big step backward. Something like a Taco ZVC panel... but you couldn't use the RTUs with that.

Your system, with the 370 running the show, the buffer tank, and the 'bang bang' boiler could actually be pretty efficient, if it's all set up and tweaked properly.

The problem with installing a mod con is getting it to operate two zones.
That really isn't a big issue. All you need is a pair of wires that tell the boiler that there is a 'heat demand'. With the existing 370, that is the 'BOILER' output dry contact closure. It would be the same with any other zoning scheme... the Taco panels have 'endswitch' relays (which is what the BOILER output on the 370 is, more or less). If a system was rat's nest wired, that same signal would come directly from the zone valve endswitches.

I'm going to spend some time reading up on the 370 this evening. Even if you 'disabled' the ODR by setting the various settings to get it 'out of the way' of the new boiler controls, you could still use it's other various functions to open and close the zone valves, start/stop the pumps, etc.

Would it be possible for you to come up with a drawing that shows how all the 'schtuff' is inter-connected on your system? This would help us understand the 'big picture' you are dealing with.

I now realize it takes water at a predetermined temperature and modulates it only by mixing it with the return water.
Sort of... in some cases... and again, depending on how it is all connected, where the sensors are located, etc.

Not only mixing with the return water, but monitoring the boiler supply (most likely) and turning the burner on/off to maintain a setpoint temperature.

It appears I am out of my depth in plumbing
I doubt it... you CAN!

"I'm Bob... I did your taxes..."

"I thought you were a tax professional?"

"Today, I'm a Master Plumber!"
 
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Old 02-05-13, 04:35 PM
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What are all the settings on your 370? Boil min, max, dipswitches, etc?
 
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Old 02-05-13, 04:49 PM
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looks like I am late to the prom dance.
IMHO, the controls on a vitodens 100 suck, I have fought many a fight with them.
I have used the open there to instruct the boiler to goto a certain temp.
We used 2 vitodens 100 boilers and a tekmar 400 series house control.

I will look at the old 370 stuff, been years since I have had to deal with them.
I would not scrap them, and we should be able to find a way to allow the use of them and still have good control of the boiler.
Just operating the boiler off TT and no outdoor sensor will just sent the boiler to a setpoint target which maybe hotter than you need.

Give me some time and I might be able to come up with a nice solution.
 
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Old 02-05-13, 04:55 PM
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looks like I am late to the prom dance.
Nope, nobody dancing yet... band hasn't even arrived. We're all still hanging around out in the parking lot drinking Southern Comfort.

I was kinda hoping you would join the fray...
 
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Old 02-05-13, 05:34 PM
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OMG, keep the SC away...
lol
 
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Old 02-05-13, 05:58 PM
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Jim, may I ask what the motivation is for replacing the boiler? - NJ Trooper

Sure, it started innocently enough in yet another attempt to save money. (Parsimony, it seems, is my most expensive habit.) Anyway, I shut the boiler off and was heating with wood. That was going so well when we had a cold snap and some wind I never thought about it. I never noticed the amount of draft that could come down that ~28 feet of chimney before. When the cold passed, the boiler was leaking and I couldn't find parts.

I thought replacement was in order, as the buffer tank is looking a little ragged as well. The fact that you asked and also considering the responses I will take the RayPak apart tomorrow, turn on the tap and watch for the bit that leaks. This system may actually
be sufficiently efficient (if a little hungry for floor space) to be the be$t bet. I am actually looking forward to it now.

As always, thanks.
 
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Old 02-05-13, 06:11 PM
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Tekmar 370 Was a very solid control, still is really.
It will not deal with a mod con well. It has no 0-10V output with which to control a modcon.

Best case, replace the current Tekmar with a 400 series house control, and the RTU's with Tn2 room stats. You will need to repipe if you have a variable speed mix pump or floating action valve in order to maximize the mod con value.
Big dollars with a new boiler and controls, no doubt.
If it where me, I would go that route.

Not knowing what your loads are, but using 30 BTU/Sqft. that 800 sqft zone is only 24,000 btu. This leads me to leave the buffer in.
A budget minded system would see the modcon feed the buffer which feeds the zones. Put some Grundfos alphas in to save hydro.

Let the Tekmar enable the boiler, but the boiler will schedule the water temp based on it's own reset curve. This would keep some features of the tekmar, specifically the zone staggering which would keep the boiler on low fire longer.
You might be able to work it so that the boiler is 5 or 10 degress F higher than the curve in the tekmar, this would bring back some of the indoor feedback the tekmar control has. But you have to be careful about how much you let the boiler get higher then the 370's targeted temperature because the 370 will start to short cycle the boiler.

In all honesty, the 370 is geared towards high mass on-off boilers, the zone staggering was created to keep the load on the boiler longer thus reducing shorts cycles. Newer tekmar controls now co-ordinate the loads to try and line up, thus loading up the boiler and forcing it to run hard against condensation.

Really with only 2 zones some of all these bells and whistles don't add up to great savings. I can tell you that the newer Tn2 and Tn4 stuff has great magic in it that learns your home and can anticipate how the room will react to weather conditions outside.

To add: forget the Viesmann...
Get yourself a NTI TFT60 boiler. Great price, great heat exchanger, great control... made in a great country :-)
 
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Old 02-05-13, 07:14 PM
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Ohhhh... now I remember where I saw the pic of the Raypack b4... you had another thread! I thought I was having Deja Vu all over again.

I knew TO was the go-to guy for this... I only have enough experience with them 'fancy' Tek gadgets to be dangerous... I had the basic idea, but couldn't articulate it like that!
 
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Old 02-05-13, 08:32 PM
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To add: forget the Viesmann...
Get yourself a NTI TFT60 boiler. Great price, great heat exchanger, great control... made in a great country :-)

Really? ....IMO viessman is superior....NTI?????
 
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Old 02-06-13, 04:38 AM
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Yes Trooper, at the time I started the second thread it seemed the topics were different enough but as time passed it became obvious it was a single thread issue. Sorry for the mind fog.

TOHeating, as you point out it is a small space so the savings resulting from techno-magic will for the most part not be realized. Letting the dog out will probably have a greater influence than a brilliantly designed control.

lawrosa, NTI has a feature not available in your area, it is based a couple of hours from here. I tried emailing a basic question (probably a list of dealers in this area) and their form required a business name so they were unavailable to potential buyers. (I often do that before purchasing technical items just to get a sense of whether the company's focus is service or marketing and if they will be available if things go off the rails.) Now, with a recommendation from a professional in the field I'll try again.

Finding a local NTI dealer shouldn't be a problem. As the wood is running low I should probably get on with it rather than freezing in a frenzy of indecision so thanks again for the impromptu education and remarkable amount of help.
 

Last edited by jwwbrennan; 02-06-13 at 05:23 AM.
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Old 02-06-13, 06:01 AM
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Why is it ?

Firetube heat exchangers are better than radial IMHO anyways :-)
 
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