TT or Veismann


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Old 05-03-10, 04:15 PM
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TT or Veismann

I was talking to the Plumbing supply house the other day as I am almost ready to start purchasing my equipment for the house. I was looking into the TT solo with an indirect but they suggested a Veismann due to the fact that I will be using radiant in one room and Cast Iron rads and a few wall panel radiators in the rest of the house. They said the Veismann can control 2 diff water temps without buying any extra controlers and the TT cannot. Anyone have any feedback requarding the 2 diff boilers in this type of set up. I plan on over radiating to keep the system temps as low as I can year round.
My issue just looking at the Veismann quickly is that it does not modulate down as far as a TT.
 

Last edited by dings; 05-03-10 at 04:34 PM.
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Old 05-03-10, 05:54 PM
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They are not exactly being accurate with you.
In order to mix different temps with the viesmann, you will need to buy the 3 /4 way mixing valve and controller from them.
That should net you about 400 to 600 bucks more.
The TT can do it, and with out much more than a cheap mix valve and power open / power close operator, but it's not as easy as it was before the Gen 5 MCBA.

Look at a Taco i-valve or simailar mix valve with built-in ODR.
If your really serious I can tell you how to program the MCBA to give you 2 different set points based on thermostat setting.

In my humble opinion the TT is by far a better product.
 
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Old 05-04-10, 12:30 PM
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TO........what changed with the Gen 5 MCBA over previous version? They are both good products.I am not sure about the Viesmann but I do not like the idea of not being able to turning down the input on the TT boiler.
If everybody did a heat loss and we did not have different heat demands or different heat loads it would not make a difference, but we live in the real world where 90% of all heating and cooling equipment is 100+% over sized. We have huge cast iron loads and small BB zones in the same home. We have radiant zones and BB zones in the same home. Add to that maybe domestic hot water loads.
For instance I had a job in Philly where the home had an old gravity hot water system and an 800 sq ft addition with BB hot water. There was no domestic h/w. The big system needed 130 at 0 and the BB zone needed 160 AT 0. The boiler was 210K which was a bit over sized for the CI system but way over sized for the HW load. The heat loss was about 160k. Dialed back the heating rpm's to match the heat loss, actually just slightly over. Connected the thermostat from small addition to the DHW terminals and dialed that fan RPM almost to minimum speed which is still twice what is needed but not near 210k input when that zone calls. This allows the water to get hotter to heat that zone faster so the boiler can switch back to heat and ramp back down. Works great, saves fuel.
 

Last edited by rbeck; 05-04-10 at 12:45 PM.
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Old 05-04-10, 03:31 PM
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With the original Gen of MCBA, I was able to add an AM3-11 module and get 3 relays that would control a 3 may floating action valve, and a circulator.
It had some nice logic to it that would allow the boiler to respond to 2 temperatures, with the boiler able to drop its target to the lower temp once the higher temp call ended.
The decided to use the option for built in 0-10 V modulation on board the MCBA not thru the AM-4 module as it once was.
Silly decision IMHO, but you can add an AM-4 and an AM3-11 module and get a second temp zone on the later gen of MCBA. It just costs more now and the settings are hard to get at with out the PC software and a certain file I have.

I understand you problem with not being able to drop the upper mod level, but I still don't think that you need to adjust that. To that end, my thought is as follows.
Assume your heat loss is 50,000 btu.
You are using a solo 110, about 100,000 output.
The PID logic is slow enough not to ramp up the burner fast, also we are going to assume that the boiler has been running on and off for weeks.
The system calls for sat 110 F, and the boiler fires.
The PID will start off at lowest firing rate until the rate of change becomes less than the MCBA wants to see. At this point it ramps up slowly. As it does ramp up water temp increases, and as it closes on target it will ramp down.
It should never exceed the target as the load is still above min modulation.
If I new what the RPM I needed to give me that 50,000 BTU was then what have I gained ? The PID logic prevents the boiler from firing to high to fast. If we did fire at 65,000 BTU for a while, is it all that bad. We are getting the water temp where we need it just a bit faster, afterwards the boiler will output 50,000 btu while the load needs that BTU output. As the OD temp changes so will the load and the water temperature right.
I guess my feeling is that since the boiler modulates with load, there is no reason I would want to limit my upper firing rate as if the OD temp dropped below that of the OD design, then the house would cool off slowly as it cannot make enough heat output to make the heat loss.
Sound right ?
Believe me, I respect your vast knowledge on boilers and there is no way I would tell you whats right and wrong. I am just trying to explain my thoughts.
 
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Old 05-05-10, 04:15 PM
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so it looks like i'll stick with the TT
 
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Old 05-05-10, 07:45 PM
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And I respect your thoughts. The problem with the MCBA is the rate of change is too fast. The Sage2 control on the market now uses the same logic as far as fan ramps up and down. The new Sage2 has new logic for fan speed and it makes a difference. It will also have the 2 curves as you say they took away.
The idea of changing fan speed is when things are grossly over sized or as in my example of two very different loads. Every mod/con will max fire at different times thought the season but will respond. The MCBA response was a bit too fast and encountered some overshooting of temps.
In my travels I see more and more techs playing with fan speed. I see it more out west than here in the east.
Thanks for the response.
 
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Old 05-05-10, 09:02 PM
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There is no doubt the boys in eng tech are pretty conservative.
I wish they could allow us techs to have access to those parameters. I did talk to Doug a while back about the removal of some of the stuff that made sense for us to have.

I am surprised you find the MCBA responds too fast. I have NEVER experienced that. Even with many small loads it's never ramped to high fire too fast. Perhaps they where too small.
You wanna see fast look at the NY Thermal Ti series, they get going up to high fire rates in a hurry.

Cheers
 
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Old 05-08-10, 04:57 PM
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Hi Guys,

I have run into a few WM Ultra's with the overshooting temps..I found these lockouts mostly when a smaller zone was calling for heat and the boiler was grossly oversized for that zone.. I lowered the fan speeds on these and seemed to have fixed the lockout issues..These were all Ultra series 1 boilers. I'm not sure which version of the MCBA controller these had.. Are you saying the MCBA in the TT solo has this parameter locked out so we can't lower the fan speed?? I wonder if the TT MCBA ramps up slower than the Ultra series 1 does?? I'm considering a solo 110 for my own home or possibly a Knight wbn105.. The knights alow you all kinds of adjustments through the laptop software..

Thanks
Ron
 
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Old 05-11-10, 05:37 AM
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Originally Posted by rharley View Post
Hi Guys,

I have run into a few WM Ultra's with the overshooting temps..I found these lockouts mostly when a smaller zone was calling for heat and the boiler was grossly oversized for that zone.. I lowered the fan speeds on these and seemed to have fixed the lockout issues..These were all Ultra series 1 boilers. I'm not sure which version of the MCBA controller these had.. Are you saying the MCBA in the TT solo has this parameter locked out so we can't lower the fan speed?? I wonder if the TT MCBA ramps up slower than the Ultra series 1 does?? I'm considering a solo 110 for my own home or possibly a Knight wbn105.. The knights alow you all kinds of adjustments through the laptop software..

Thanks
Ron
Ron,
Triangletube does indeed lock out these parameters.
You can use the exact same cable and software from WM on the TT.

As far as overshooting, good flow thru the boiler can help to prevent over shooting due to low load. Add a buffer tank t the system, or try to schedule the load to come on only when other loads do (not so easy).

Micro loads and low mass boilers are a problem today, buffer tanks seem to be the best fix.
 
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Old 05-11-10, 07:18 PM
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Thanks TO,

These were 2 ultra installs done by others that I took a look at for a couple of friends.. Both installs were piped correctly with primary/secondary and with the proper circs for flow through the boiler..However the original installers sized them comparable to the boilers that were removed..As you can imagine without a heatloss calc, the ultras were indeed oversized.. After cleaning them and changing the fan speeds, both seem to be working good for the last 2 years with no lockouts.. In the future I told both friends that I would like to try combining zones and going more for constant circulation and lower boiler temps to save them some money.. As far as my situation, I'm looking to replace my old boiler with either the TT or the Lochinvar knight..

Thanks

Ron
 
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Old 05-11-10, 07:34 PM
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just my 2 cents...
I'd go Triangletube myself, I just love the heat exchanger.
They will all have new controls very soon as the MCBA is going bye-bye soon.

There are WAYS to get at the fan speed settings, but you may end up with a fight from the factory if anything went wrong.

Cheers
 
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Old 05-11-10, 08:13 PM
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Hi TO,

Thanks again for your input..Since I will be doing the install in my own case and have already done my heatloss calcs at 69,000 btu, the TT 110 or the Knight 105 should work out nicely..I'll be doing constant circulation with a boiler temp of around 130 and 30 degree delta T so I should be condensing nicely..Hopefully I wont need any access to fan speeds, I was just curious why WM let us have access to them and TT didn't..Is TT new control much better than the MCBA or is the MCBA being discontinued?? Maybe I should wait for the late fall to pick up a solo 110 and maybe the new controls will come with it..


Thanks
 
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Old 05-12-10, 09:03 PM
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I do not know when the new controller will be released.
The MCBA has / is being discontinued (to my knowledge).
I will miss it.

I doubt TT will allow access to the fan speeds. They actually did on the first gen MCBAs. They could not customize the installer access features on that model as they can do now.

The good thing about the TT is it's low head loss thru the heat exchanger. It's very possible to pump the house thru the boiler while using only the built in 15-58 circ in the solo
 
 

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