Smart thermostat for hydronic radiant floor heat ?

Tarpan

Hi there,

Can you recommend me a Smart thermostat for hydronic radiant floor heat ?
Basic requirements:
- 2 stage heat (radiant / forced air)
- 1 stage cool
- remote (smartphone) connectivity
- SmartHome integration is a plus

Obviously the thermostat should be able to control radiant floors. I got Ecobees now, have many issues, mostly due to lack of radiant floor heat control. Nest seem like a next logical choice.

Thank you in advance
Alex

Jamie Hall

Nest is worse. Radiant floor heating can't be properly controlled with a wall thermostat, except to "trim" the heat. What is needed is outdoor reset which will control the temperature of the water going to the floor -- which is always circulating. You don't want to try to use any kind of setback on a radiant floor, as it responds much too slowly. A wall thermostat, in addition, can be used to trim that for odd conditions, but the basic control is the outdoor.

With your setup, it sounds as though you have forced air supplemental? I'd forego the trying trim the radiant floor, and just use a properly adjusted outdoor reset on your boiler and mixing valves and use the forced air to trim.

Derheatmeister

Not a big fan of Nest..
Nowadays we like to use tekmar 564 or Ecobee's.
We really liked the older Ecobee 02 but they have been discontinued.
Which one of the Ecobee's are you using now?
Are you trying to perform setback scheduling with it ?
With Radiant floors you should "set it and forget it"
Some of the Tekmar has thermostats/controls utilize PID algorithms to which it will assist with fluctuation due to external thermal gains.
Hope this helps.

MikeL_2

         I agree with Jamie. We have 8 or 10 radiant floor systems that are fed by hydronic mixing blocks ( Viega, mostly ) & no tstats. The swt is determined by a heating curve and is adjusted continuously based on outdoor reset.......

Zman

Tekmar...

Tarpan

Jamie Hall said:

Nest is worse. Radiant floor heating can't be properly controlled with a wall thermostat, except to "trim" the heat. What is needed is outdoor reset which will control the temperature of the water going to the floor -- which is always circulating.

I guess it's what I have. Viessmann modcon with OR dumpen so low so it would take a 1-2 hours to raise a temperature by a degree. As a result, the boiler chugging along for hours circulating water non-stop. Next, room thermostats are "a must" as different rooms react differently (solar gain, etc). I guess it's what you call "trim".

A problem I have with Ecobee4 - it has an idiotic setting "Stage 1 max runtime" which can be set to up to 2 hrs. So after 2 hrs for heating floors, thermostat just kicks on the forced air and shuts off the floor till temperature drops again. :-(

Jamie Hall said:

You don't want to try to use any kind of setback on a radiant floor, as it responds much too slowly.

Actually, I would love to have a night setback. 1st of all, it just feels more comfortable. 2nd benefit - reducing heat loss overnight, assuming I can raise the temperature quickly in the morning by running forced air in addition to the radiant floor.

Ecobee fails here too - it runs forced air "instead of", not "in addition to" the radiant floor.

Jamie Hall said:

With your setup, it sounds as though you have forced air supplemental? I'd forego the trying trim the radiant floor, and just use a properly adjusted outdoor reset on your boiler and mixing valves and use the forced air to trim.

The house used to be forced air. I have added staple-up radiant. So essentially forced air is now supplemental (or 2nd stage). I don't think "always-on" floor is a viable option due to differences in room heat loss characteristics - for example south-facing Master bedroom stays warm during sunny days all by itself.

I'm curious why you said Nest is even worse - Nest have support for radiant heat, they call it "True radiant". That should help.

Tarpan

Derheatmeister said:

Not a big fan of Nest..
Which one of the Ecobee's are you using now?
Are you trying to perform setback scheduling with it ?

Ecobee3 and 4
I like 3 more - it works better. Ecobee4 causing more troubles.
Yes, a couple degrees nightly setback. Most of issues are related to Ecobee failing to recover properly from the setback in the morning.

Jamie Hall

The problem with a radiant floor and setbacks is simple physics. Even light weight ones, like your staple up, will take several hours of steady running to recover from even a two or three degree setback.

As I said, your best bet is going to be to run the radiant as it should be run, on outdoor reset, to hold a comfortable low temperature -- whatever you fancy, such as 68 -- and leave it alone. Then use the forced air -- running of a Nest or whatever you want -- to boost the temperature when you want.

As to the problem mention with undesirable balance between rooms, if the rooms are on different zones -- which they certainly should be, if their heat lose and gain characteristics are different -- you could use room wall thermostats to close the too warm zones. Frankly, if they are all on one zone, you're kind of out of luck;

TAG

I had a friend try and use a heat pump thermo to do what you wanted to do .. it sort of worked. He wanted the setback ..and thought that the emergency heat would just flip on the HVAC .... in cycled too much.

You have a great boiler with ODR -- just set it low to maintain a temp and use the HVAC to raise the temps. The problem you have is the slow response of the staple up .. and what you want to do requires more zoning for both systems.

I have done this before and have it in my new house .... but you need many thermostats and zoned HVAC to make it all work

pecmsg

Radiant floor & Heat Pumps................ Set them and forget them. There designed too match the Heat Loss not rapid changes in temperature.



and there's Nothing Smart about N E S T!

TAG

The nice thing about radiant in a large house w/ many rooms is the ease of "zoning" if you think it out before hand .... I ended up using Cross manifolds in my latest project for the ease of adding thermostats and controlling the various zones. It's an odd space with various heat loads per SF and some areas with solar gain. It's a weekend house so there will be times when I need the HVAC's propane furnace to bring the house up to higher temps if it's been empty for a couple weeks. But -- the best way is to set the ODR and control the upper limits using a floor thermostat when you want them a little colder. This way the HVAC will not change the individual room.

Derheatmeister

We had some customers that had "Dips" in their Great Room temperature due to Sunsets and sunrises.
A Tekmar with a PID logic can help with those situations.
Again.....As mentioned by many professionals in this tread with Radiant Floors you should "Set it and Forget it"
If the setback you are trying to achieve it is a energy savings driven setback....Your going to waste more energy in the Recovery period.
If it is a Comfort driven setback,faster heat surface area such as European Radiant panels or radiant walls can be a great benefit. Air can also assist with this.but in my opinion the control needs to be of a better quality such as a Tekmar with a PID feature.
Sounds like you may have some other huddles to overcome and a Nest, Ecobee may not be your cure all..
Do you have a Plateless staple up with the Air ?
Did you negotiate your Boilers time response and is yor curve,shift set based on you systems requirements.
Hope this helps.

River

I use the Tekmar 564.
My radiant floor is on heat stage 1, furnace supplemental heat is on heat stage 2, I have a floor sensor attached to it, and it monitors the temperature outside. It also controls my A/C and I thinking of adding a humidifier to my furnace and the tekmar 564 will control that to. The Tekmar 563 or 564 are designed specifically for hydronic heating systems. I called Tekmar for advise before I made the purchase, the call back service was great so I wasn't on hold forever and the technician understood what I wanted it to do and helped me with the setup.

Can I ask what your staple up system looks like?

Derheatmeister

River said:

I use the Tekmar 564.
My radiant floor is on heat stage 1, furnace supplemental heat is on heat stage 2, I have a floor sensor attached to it, and it monitors the temperature outside. It also controls my A/C and I thinking of adding a humidifier to my furnace and the tekmar 564 will control that to. The Tekmar 563 or 564 are designed specifically for hydronic heating systems. I called Tekmar for advise before I made the purchase, the call back service was great so I wasn't on hold forever and the technician understood what I wanted it to do and helped me with the setup.

Can I ask what your staple up system looks like?

We also Install the 564 ,we like it but here are some of the Disadvantages /shortcomings.
1. Humidifier setup: Although the Thermostat has a humidity sensor built in we like to base our humidifier process on the OD temperature in order to prevent condensate forming on the windows...I know that the 564 has a window schedule but years of experience with Humidifiers has given us better results with OD influenced operation such as April Air's setup.
2. Radiant Floor setup: This Thermostat doesn't have an option between Light or Heavy mass like the older Tekmars had..The Extra floor sensor may assit ,but this feature helps with the PID function
3. No PID : As mentioned above The PID function was a great benefit to help prevent "Dips" in the temperature...See it functioning as "The Midnight movie Starts at Ten" so you will make it on Time ... In other words:Although at the moment your a room is not calling for heat ,the control may turn on the heat to that zone in order to maintain certain setpoint in the future base on a history of feedback gathered over a couple days ,I know that this thermostat has a "Early Start" which may use a Additional OD sensor but that's not quite the same.
4. Water sensor Setup: The Water shutoff cannot be shutoff remotely and the placement of the sensor is also very crucial in order for this to work..Moen Flo and Steamlabs have better setups that are also programmable and can be shut off via the app..
5. E Mail notifications:Only one person will be notified if a setpoint not achieved..Ecobee allows for Additional notified on the account.
6. Wiring Center: In a couple weeks we will be installing six of these in a residential application, The real estate that this is going to take up in the mechanical room is going to be enormous and it would be Great if Tekmar had a smaller wiring Center (Zone Contol Center)for this Type of situation.
Don't get me wrong, We really like this thermostat,the price point is also good,As you said Tekmars Customer services are very good and they are very knowledgeable,but this stat also has its limitations which also may not "Fix" Tarpans situation.

It still would be nice to know how the tubing was installed and if the time respond feature on the Viessmann was setup.

Prevch

Tarpan said:

Jamie Hall said:

Nest is worse. Radiant floor heating can't be properly controlled with a wall thermostat, except to "trim" the heat. What is needed is outdoor reset which will control the temperature of the water going to the floor -- which is always circulating.

I guess it's what I have. Viessmann modcon with OR dumpen so low so it would take a 1-2 hours to raise a temperature by a degree. As a result, the boiler chugging along for hours circulating water non-stop. Next, room thermostats are "a must" as different rooms react differently (solar gain, etc). I guess it's what you call "trim".

A problem I have with Ecobee4 - it has an idiotic setting "Stage 1 max runtime" which can be set to up to 2 hrs. So after 2 hrs for heating floors, thermostat just kicks on the forced air and shuts off the floor till temperature drops again. :-(

Jamie Hall said:

You don't want to try to use any kind of setback on a radiant floor, as it responds much too slowly.

Actually, I would love to have a night setback. 1st of all, it just feels more comfortable. 2nd benefit - reducing heat loss overnight, assuming I can raise the temperature quickly in the morning by running forced air in addition to the radiant floor.

Ecobee fails here too - it runs forced air "instead of", not "in addition to" the radiant floor.

Jamie Hall said:

With your setup, it sounds as though you have forced air supplemental? I'd forego the trying trim the radiant floor, and just use a properly adjusted outdoor reset on your boiler and mixing valves and use the forced air to trim.

The house used to be forced air. I have added staple-up radiant. So essentially forced air is now supplemental (or 2nd stage). I don't think "always-on" floor is a viable option due to differences in room heat loss characteristics - for example south-facing Master bedroom stays warm during sunny days all by itself.

I'm curious why you said Nest is even worse - Nest have support for radiant heat, they call it "True radiant". That should help.

I have a similar set up. My main heating source is in floor radiant driven by a boiler and I have backup emergency heat from an electric coil in our forced air system.

I have a total of 8 nest thermostats.

7 nest thermostats control different zones for the in floor heating.

1 nest thermostat controls the forced air system (heat or AC depending on the situation)

Works good for us.

Jamie Hall

Cedric is controlled by one 50 year old Honeywell Mercury T87 for 7200 square feet on three floors. Heat is even, comfortable, and simple. What's not to like?

Derheatmeister

Jamie Hall said:

Cedric is controlled by one 50 year old Honeywell Mercury T87 for 7200 square feet on three floors. Heat is even, comfortable, and simple. What's not to like?

Hypocaust....4 foot Stone Pillars supporting 5' x 5' Stone slabs to create a Duct/Crawler,Controlled approx. at 100 AD by a Roman holding a Whip and a POW german marking a Fire in a pit.Heat is even compared to a regular fireplace,Comfortable, And Simple .Guess the Romans liked it.Maybe the POW didn't like it at all.
Richard.

pecmsg

Jamie Hall said:

Cedric is controlled by one 50 year old Honeywell Mercury T87 for 7200 square feet on three floors. Heat is even, comfortable, and simple. What's not to like?

and that T87 is Much Smarter then the NEST!

JimP

I'd avoid the Nest. I have four Nest thermostats and remote sensors sitting on a shelf after in use for a couple months. Our utility had a deal where they cost about $50 so I tried them out. They didn't work well and I've gone back to a simple thermostat which works fine. Heating contractors in our area install the Ecobee if a customer wants a smart thermostat.

jalagna

I have TEKMAR 563 stats for radiant and heat pump secondary. Can anyone explain how to set so it works off the floor temp and not the air temp? My floor always feel cool, stat makes air temp but the floor temp always says 69. Please advise settings. 

hot_rod

jalagna said:

I have TEKMAR 563 stats for radiant and heat pump secondary. Can anyone explain how to set so it works off the floor temp and not the air temp? My floor always feel cool, stat makes air temp but the floor temp always says 69. Please advise settings. 

If the air temperature is maintained at a comfortable temperature, raising the floor temperature via a floor sensor will cause the space to over-heat

Typically the floor sensor is working in conjunction with the air sensing function to prevent over shoot

I’m not sure where you are reading 69 degrees. Certainly a. 69 degree floor surface could not heat the room to 70? Must be some other heat being added. 10,000 btu or more of internal gain is not unusual.
Cooking, appliances, lighting, even occupants all add to the heat energy in the building.

jalagna

I have a heat pump & radiant on my kitchen zone. During heating season the radiant is primary and heat pump secondary. Through the stat the floor sensor shows 69 degrees, I was wondering if I can basically shut the heat pump and use only radiant and maintain a higher floor temp.  

hot_rod

It is a challenge to have two heating systems work together especially a slow moving radiant and a faster responding HP. To feel warm, or even neutral the floor needs to be 80° or so, close to bare foot skin temperature.

An 80° degree floor will give off about 20 btu/ sq ft in a 70° space. And then once the thermostat is satisfied, the floor will slowly drop in temperature.

On a cold, design day, ideally the floor runs constantly and maintains the warm feel.
Shoulder season, or mild days, you may not always maintain that warm floor sensation.

Floor sensing controls work well for tile bathrooms, where you can maintain a warm floor throughout the year. Knowing that it could add to the AC load

In a bathroom the control could either maintain a temperature, a not to exceed temperature, maybe 80F
Or program so it doesn't drop below a temperature maybe 76- 78. Something above above whatever ambient the home or room is maintained at. Tile floors at 76- 78 will still feel a bit cool if you feet are 80- 82, for example.

Comfort is very subjective.

jalagna

How do I raise the floor sensor on the stat, Is it just setting the minimum to the 80 degree mark? Right now on the stat the floor sensor is showing 69. 

hot_rod

The tekmar 518 was my favorite basic stat with a floor sensing option.
file:///Users/bobrohr/Downloads/Tekmar-518-Install%20Instructions.PDF


Looks like the 573 has more features. And price. Attached below is the floor sensing options and setup page.

You need to look at the installation sheet for the thermostat you are considering.

jalagna

I have the 563 installed but what you sent works! Thanks!! I just need to figure a nice minimum temp for the floor

HVACNUT

jalagna said:

I have the 563 installed but what you sent works! Thanks!! I just need to figure a nice minimum temp for the floor

I usually set clients minimum floor temp to 70° until I come back around for an A/C maintenance and turn them off.
Not a fan of WiFi thermostats in general, and especially not for radiant to play with on your phone. Just the other day a Caretaker said the owner wanted something to program remotely. The current Tekmar 501's are doing fine at maintaining setpoint. I told the Caretaker to please relay the message for radiant is to "set it and forget it" but if the client wants what he wants, who am I to argue? It's not my house, so I recommended the 561. Nine of them actually.