32 T-stats

Zman

I am looking at a job with 32 T stats. The entire house is high mass radiant. The original designer determined that spaces in the room had very different heat loss characteristics and ran 3 different temp supply and return mains throughout the house. A high heat loss rooms manifold is tapped into the hotter loop, the lower loss room into the lower temp. The t stats are in the rooms and have 3 wires run to them. The zone valves and zone controllers are scattered all over the house with just 3 wires running back to the mixing controllers in the mech room.

The owner would like to have room by room control from anywhere. I have pretty much settled on the idea that the new t-stats need to be 3 wire with wireless communication. I like the Tekmar 561 because it has some nice features for high mass floors but am open to suggestions. What I am trying figure out is how do all these t-stats get managed on the user interface? It is a second home that is sometimes occupied by 2 people and sometimes by 20. The owner would like a simple interface where you can enable scenes depending on who is coming to town.

Thank you in advance,

Carl

nicholas bonham-carter

Is it really necessary to have such control over 32 zones?
How low a temperature are the unused zones being turned down? When many are dialed down, will there be a short cycling problem? Would trvs on the radiators help out here, even though it will require a visit to the room, (they should do that anyway to make sure all is ok).
This is a setback situation to end all setbacks!—NBC

Zman

I have considered combined some of the zones and am considering short cycling in the new boiler design.
Even combining zones, I am looking at more than 20.
Keep in mind that the shanty is 16,000 sq ft.

the_donut

It might make sense to stage multiple boilers in this situation.

nicholas bonham-carter

Who was the original designer of this system, and when was it installed? Was an accurate heat loss ever performed? Is there any outdoor reset in the system? In such a case, the recovery may be slow, so as to make the thermostats unnecessary/undesirable.
Staged boilers would be ideal, if there is space in the mechanical room, and if outdoor reset can control more than one boiler.
Can any improvements be made to the building envelope to reduce heat loss?—NBC

Jamie Hall

I have to go to the dump right now, Carl -- Ill think on this one while I'm doing that. I have a germ of an idea...

Harvey Ramer

Can you use the Tekmar 485 Internet Gateway and the 479 User Switch to accomplish your goals. That's one of the easiest ways to get the tekmar thermostats all under one roof and make universal switches and scene selections.

Zman

Harvey Ramer said:

Can you use the Tekmar 485 Internet Gateway and the 479 User Switch to accomplish your goals. That's one of the easiest ways to get the tekmar thermostats all under one roof and make universal switches and scene selections.

Harvey,
I don't have the wiring to do a TN4 or TN2 system. Is the gateway compatible with the wireless?

Zman

nicholas bonham-carter said:

Who was the original designer of this system, and when was it installed? Was an accurate heat loss ever performed? Is there any outdoor reset in the system? In such a case, the recovery may be slow, so as to make the thermostats unnecessary/undesirable.
Staged boilers would be ideal, if there is space in the mechanical room, and if outdoor reset can control more than one boiler.
Can any improvements be made to the building envelope to reduce heat loss?—NBC

The house was built in 2001. I performed a complete heat loss off the drawings. Upon visiting the job, I found the original design and heatloss. I was within 5% of the original design. The number is around 280,000.

The boiler plant, buffer and mixing is another subject. I am leaning towards (3) Lochinvar's using on-board cascade and mixing controls.

Harvey Ramer

Zman said:

Harvey Ramer said:

Can you use the Tekmar 485 Internet Gateway and the 479 User Switch to accomplish your goals. That's one of the easiest ways to get the tekmar thermostats all under one roof and make universal switches and scene selections.

Harvey,
I don't have the wiring to do a TN4 or TN2 system. Is the gateway compatible with the wireless?

I'm not sure if it is Carl. But surely there would be a base unit connected to the thermostats that would be compatible?

Tim Potter

"The owner would like to have room by room control from anywhere."

Seems to me Mark Eatherton uses a system that can be adapted to however many t-stats you choose, & internet controllable.

Mark Eatherton

http://www.climateautomationsystems.com

Thanks Tim!

Full disclosure, I sit on their technical advisory board. Not sure this is really a good fit, but can't hurt to look into it. Having the control devices spread all over creation may pose a problem.

ME

HVACNUT

@Zman, many of our accounts use Crestron Home Automation.
Usually installed by those "smart home" guys and gals.
I can navigate the HVAC through one of the iPads mounted in the walls of the home. Usually one on every level. The homeowner will have remote access to all settings, make adjustments, and get alerts.
Each zone can be operated independently.
Disc room temp sensors throughout.
I don't know if the wiring will configure, but it's worth a look.
www.crestron.com

Zman

Thanks to all have responded.
I am leaning towards either making it simpler by combining zones and using a Tekmar or HBX wireless (wired for control) t-stat or going fully custom, either with custom HVAC controls or part of a high tech automation system.

Jamie Hall

The only coherent thought I have, @Zman , is to be cautious about raising expectations too high -- since this is a high mass radiant system, it is going to respond very slowly to inputs, and the owners need to be aware that it may take a little time for a space to respond to its thermostat... nothing you can do about that, even with the most sophisticated controls.

Zman

@Mark Eatherton
I am intrigued with that product. I have been looking over plans and photos of the job and I think I could get Ethernet to the 3 locations where the existing controls are located.

Are you familiar enough with the system architecture to know if 3 modules can be tied together with Ethernet to create 1 system?
I know Honeywell Niagara can do this via multiple jaces.

Carl

Zman

Jamie Hall said:

The only coherent thought I have, @Zman , is to be cautious about raising expectations too high -- since this is a high mass radiant system, it is going to respond very slowly to inputs, and the owners need to be aware that it may take a little time for a space to respond to its thermostat... nothing you can do about that, even with the most sophisticated controls.

Jamie,
I agree completely. The owner understands the high mass part of it. The home presently has undersized boilers and manual t-stats. They understand how long it can take.

My biggest concerns are systems that over promise or are overly complex.

This project is also a long way from home for me. They will need to find locals who can work on it.

nicholas bonham-carter

What is driving the desire for these changes? Are they ever uncomfortable, with the present system? Are the fuel bills too high?
One of the benefits of a simple system is the ability of the homeowner to diagnose simple faults, and fix himself, or at least describe them to the installer.
When bedroom 6 is chilly, check the TRV setting, and feel the radiator. Cold rad, then look at the pump, etc.
With these sophisticated controls, the added layer of complication can be confusing. Some areas will respond differently, with regard to speed of recovery, and aunt Edna will still be chilly while the Outdoor reset slowly catches up.
Some internet control over the whole system could be useful at the beginning, while the parameters are being tweaked, but to have it room by room may be overkill.
Putting an inexpensive digital thermometer in each room would show them the true temperature, instead of just relying on feeling.
The only use I can see for this is being able to heat a room up to 125 degrees to kill any bedbugs!—NBC

Zman

I think some of the motive is energy efficiency and some is comfort and convenience. Peace of mind that the home is heating properly when unoccupied and satisfying the inner geek also plays a part.

It is presently a total pain to walk through the house and check that the t-stats are functioning correctly and that the guest who just left did not crank it up to 85 because they were cold the night before (usually because they turned it up to 85 2 days before then down to 50 because they do not understand radiant).

If this was mine, there would not be a t-stat in the house. Every zone would have a sensor tied into a control system. Each room would have a mini I pad sitting on a charger. From there, the guest could run the AV system, turn on lighting scenes, set an alarm clock, check the news, and change the room temp.

When the house is unoccupied (could be a month or more), all the t-stats would go to the setback setting. A day before a planned visit, the owner's personal assistant. turns up the heat and enables the occupied lighting scene.

Mark Eatherton

Zman said:

@Mark Eatherton
I am intrigued with that product. I have been looking over plans and photos of the job and I think I could get Ethernet to the 3 locations where the existing controls are located.

Are you familiar enough with the system architecture to know if 3 modules can be tied together with Ethernet to create 1 system?
I know Honeywell Niagara can do this via multiple jaces.

Carl

Carl, I'd suggest that you contact the [resident of the company, Ron Antinori. Although I am an advisor, I haven't had a chance to get caught up on their most recent innovations.

Ron can be reached at 404.875.7063

Tell him I said hey.

ME