Thermally Controlled Diffusers

[Will]

Which brand of thermally controlled diffusers offer the widest range of temperature set points? In particular I would like to find a way to set temperature between 69 and 71 for a unit that has both heating and cooling thermostats built in.

Acutherm makes the Therma-Fuser product, and it has a set point range between 70 and 78.

I'm also interested in finding alternative products that have digital wall thermostats to allow the end user to have some input into the thermofuser set points. Acutherm appears to have this.

If there are any brands to avoid I would appreciate knowing about those as well.

[Zyp]

Anything that limits the air flow through the diffuser is not good for the equipment. Generally, when there is less than the recommend airflow, it is condsidered abuse by the manufactuer.

I realize that many believe that zone controlled diffuers [new to the market - some wireless] will solve poor duct design, but nothing is further from the truth.

[Will]

I think the Acutherm wireless thermostat for their therma-fuser just alters the set point on the thermostats inside the diffuser. It doesn't alter airflow directly?

Sometimes it is not an airflow problem. Sometimes the problem is a large area is on one zone and the thermostat placement for the zone doesn't accurately represent temperature variations across different rooms.

And the therma-fuser gives each room occupant at least some ability to establish a personal preference a bit warmer or colder than the set point on the zone thermostat. I know some large companies here in the Bay Area like Adobe put a therma-fuser on every outlet vent going into an employee's work area.

[Noon-Air]

Just how do you think they work if they don't alter airflow directly???

Unless the thermostat is placed on a window or in the other end of the building from where the zone is, thats not really an issue, neither is the size of the space. What IS the issue is proper airflow and distribution. There are minimum airflow requirements for a/c systems.. usually around

400CFM per ton. If you increase or reduce the airflow by as little as 10%, the consequenses can be disasterous. too little airflow, and the system will freeze up, too much airflow and you have high humidity...that creates its own set of problems. FWIW, a correctly sized system, with a properly installed air distribution system will maintain a constant, even temperature throughout the zone....usually within 1 or 2 degrees.

They don't work like that.

As far as I can tell, either your trying to put a band aid on poorly designed, badly installed, air distribution system(ductwork), or you spamming these "smoke and mirrors" defusers. which is it??

[Will]

Thermafusers alter the airflow as a result of an internal thermostat responding to airflow temperature around the thermostat. The wireless thermostat on the Acutherm unit appears to alter the setpoint temperature of that thermostat.

Room A on Zone 1 can set the thermofuser to close its damper below 70 and above 72.

Room B on Zone 1 can set the thermofuser to close its damper below 71 and above 74.

That certainly does affect the end temperature in each of those two rooms. It's not active heating or cooling from the therma-fuser, but it is certainly giving the room occupant some level of control on the end temperature, and at least it sets limits.

Badly designed, badly installed, badly redesigned, badly maintained systems with bad ductwork describes about 90% of the small commercial buildings that are 20 years old. And no one ever has the $3K to $10K budget to redo a zone. Usually the customer has a problem with a single room even *after* everything is rebalanced.

In any case, I was looking for brand recommendations for thermally controlled diffusers. I wasn't trying to convince anyone to use one.

[Noon-Air]

They "alter" the airflow by restricting it.... just how much restriction in the airflow do you figure that its gonna take to make the system freeze up?? or to make the furnace to trip on an overtemp safety??

Its *STILL* nothing but smoke and mirrors and restricting the system airflow. You can argue all you want, that is still not gonna make it right.

Thats only because there are hacks that will cut everybody elses throat to get a job, even if they do the job at a loss. *competent*, professionally trained, HVAC techs know what their time, training, education, and expertise is worth, and will charge accordingly. I'm sorry that your having to contend with the results of having the lowest bidder do the job. Thems tha brakes.... get it right or get it cheap. BTW.... putting bandaids on the system with smoke and mirrors defusers, is not going to *fix* anything.... only make the original problems worse.