Smart Boost on Energy Kinetics with Nest True Radiant

hughbucks

I have an EK Accel system connected to Nest thermostats.

Nest has a feature called "True Radiant" that seems to conflict with "Smart Boost" feature. As I understand it:

* Smart Boost on the EK will crank up the furnace if boiler isn't able to satisfy the demand after a set time (either 20 minutes or 45 minutes). Don't understand all the terminology regarding reset curve, but from what I gather the furnace is less efficient after this mode kicks on with the benefit of it preventing the system from taking forever to bring the house back to temp.
* Nest has a feature called "True Radiant" that basically says "I know newer radiator systems can take a long time to heat up; tell me when you want it to be 72 and I'll tell the thermostat to come on X hours earlier in order to satisfy that", learning as it goes.

If you have a Nest, wouldn't it be more efficient to turn the "True Radiant" on and have the boiler run longer in the more efficient mode vs use Smart Boost?

STEVEusaPA

Hang tough, a few of the EK people regularly check the site. They will have the best answer for your.
But it does seem like conflict and I would rely solely on the Smart Boost from the EK and not the 'True Radiant' from Nest. You can search this site to see all the problems with Nest. There's also no way Nest was ever tested (by Nest) against the smart logic of an EK.

Generally with hydronics and specifically with radiant heat, deep set backs and very long recovery are not recommended. In a properly designed system you should only be able to recover 1, maybe 2 degrees per hour on colder days.

brnrman1

Hughbucks,
Steve is right with in floor radiant heat. The best plan is to set the thermostat at whatever comfort level you want and leave it there, in particular if recovery takes a long time. In floor radiant heat by design is like a flywheel - once you get it going very little heat is needed to maintain it. The Accel CS boiler is a modulating condensing boiler and will be very efficient by matching the heat input to the heat output.

The Nest true radiant concept sounds basically like an extension of the heat anticipator in the thermostat as it will start heating and circulating water to get the space up to temperature so it’s at the temperature you want when you want it there. This is assuming you are turning the heat down at night or at other times. I would recommend you leave the thermostat setting alone once you have the space heated.

The Smart Boost feature of the System Manager is intended to be used with mixed radiation types or non-“in-floor” radiant where you might have a setback. Smart Boost will raise the Boiler water temperature up to 30 degrees above the original target temperature based on the duration of the thermostat call for heat. The purpose is to heat the space as soon as possible for comfort and then finish the cycle in Energy Recovery Mode to capture higher efficiency. Energy Recovery uses the residual heat in the boiler in the heating zone that was calling for heat.

I hope this clears up your questions and will help you keep your Home comfortable and efficient.

Mitch
Roger Mitchell
Energy Kinetics

mattmia2

It seems like ideally the boiler control and the t-stat would be all one unit so that it would know if it is trying to hit a setback recovery target and can calculate how to get there efficiently and would know if a long call is because it is trying to gain 10 degrees in the space or it is because it successfully matched the output to the load. I don't know if there are residential systems that do this and it inherently is somewhat proprietary so it makes future parts availability a bit of a concern.

Roger

Good comments all around!

The first point is comfort:
As we are talking about in floor radiant, which has a very long lag between thermostat call, boiler temperature, and room temperature response, the best solution is typically to maintain temperature in the slab and at the thermostat.

No matter what thermostat and boiler temperature is used, it can still take hours to recover temperature with an in floor radiant system.

A very good way to improve recovery time is to heat with hydro air in the same zone for quick pick up from setback.

The second point is efficiency:
Because of the way Energy Kinetics boilers run with energy recovery, the operation is very close to peak efficiency regardless of boiler temperature. A few points can be gained by running the boiler with lower return temperatures to increase condensing, but the temperature is ultimately established by the type of radiation and the temperature required to provide proper comfort and response time to thermostat calls.

@hughbucks , if your heating professional is very confident with the appropriate reset curve to heat your home, and your home is all radiant, then SmartBoost can be disabled. If you have mixed types of radiation, or there is any question about the reset curve providing even and responsive heat, then enabling SmartBoost will do exactly what a heating pro would do: increase the boiler temperature when heat response is not fast enough. It also changes back when not needed and is specific to each zone.

Best,
Roger

DanHolohan

The owner of the company answers a customer's question early on a Saturday morning. EK continues to impress. Thanks, Roger!

Roger

You’re welcome, Dan - it’s great to participate and to see how everyone comments and helps out here!

hughbucks

Roger, it's baseboard radiant, not in-floor (I can dream though). I only set the temps back maybe 4-5 degrees at night, mostly because we like to sleep with it colder. With our previous oil furnace, I was much more aggressive at night and when we were away for the day in an attempt to save some $$ but that doesn't seem to make sense with our new system.

Only problem with this approach is if we go away for a week or two during the winter. I would turn the heat down much lower in that case (like 55), but then when I turn the thermostats back on, it will take a *long* time to come back up without SmartBoost. Kind of wish there was additional options for the time.... like if after 3 hours, it's still not to temp, forget any efficiency gains and crank it. That happens rarely enough that I could just turn SmartBoost back on for those weeks.

With the Nest app, you can see it coming on earlier on colder days to get to the right temp and it rarely overshoots so at least it looks like it's working. On colder days, it does take a good 2-3 hours to go from 64-69 but I'm asleep so I don't really care about that. And maybe this is all in my head, but I find the air less dry in the morning without SmartBoost as the radiator isn't getting as hot.

Roger

Good information, @hughbucks !

It sounds like you are happy with your recovery time without SmartBoost, so you can leave it turned off. I would recommend you either:

1. Change your thermostat setting remotely (from Away to Home on your NEST) in time for your home to recover before your return.
   

-OR-

2. Leave SmartBoost on for faster recovery as your system will be very close to peak efficiency regardless of boiler temperature.
   

Regarding dryer air, I would think that a 30°F change in hydronic supply temperature would not have a noticeable impact on relative humidity (outside combustion air is always connected on Accel CS boilers which isolates the boiler from the house, and you are keeping the house at the same temperature/thermostat setting so there should be no comparative thermal driven infiltration change). Furnaces (forced air systems) can impact relative humidity from changes in pressure in the house due to leaky duct work and the respective negative or positive room pressure impact (from dryer infiltration air in the winter for example).

Best,
Roger

bigiron

New home owner here researching about oil to gas conversion and new boiler. Just want to say that seeing the company president helping out someone in a public forum gives me a really good feeling about the company and their product.

Roger

Thank you for such a tremendous compliment, @bigiron - HeatingHelp is an excellent forum that allows us to extend some of the family owned business communication and support that is at the heart of Energy Kinetics. Please let us know if we can help further with any questions - we have a capable and engaged team all around.

nymedic

Thanks so much for posting on this forum Roger.
I have had a oil fired system 2000 ek1 since may and i love the system . Quick question about the smartboost
I do a 8 degree setback at night(70 to 62). With outdoor temperatures in the low 30s my baseboard recovery in the morning is around 4 hours. It will go up to 5 hours when really cold in the teens. I think my recovery times are not bad for hot water baseboard heating.
Do you think it would be worthwhile to turn on the smartboost to decrease the recovery time. I'm wondering if the increased oil use from the higher operating temp of the smartboost might be canceled out by the reduced boiler run time in recovery. And would it be better to use the 20 min or 45 min setting on the smartboost if it is turned on.

Thanks again - any insight provided would be greatly appreciated
Anthony

SuperJ

I don't have any EK experience but have done a lot of commercial buildings with aggressive setbacks and recovery.

Commercially, we try and hurry up and finish with recovery. We will allow the boiler temperature to run hotter during morning warmup to speed the recovery (it's reset upwards based on zone heating requests similar to the EK strategy). This allows the building to coast longer on the setback before hitting the "afterburners". So heating might start at 6:30am instead of 4:30am for an 8am occupancy target.

It generally saves more energy by delaying recovery, even if you have to run a bit less efficient to recover (so I would recommend leaving smart boost on regardless of the nest setting). The nest will likely adapt to the quick recovery and wait longer to call for heat on recovery.

This works because the lower your heating setpoint the less heat your building is leaking per hour. It's a trade-off between high boiler efficiency (ie. low temp water) with long recovery(not efficient), or a cooler building for longer (saves energy) but less efficient boiler (hotter water).

One caveat with commercial systems (versus residential), is that outdoor air heating plays a much bigger part and is a huge load. So keeping the air handlers off as long as possible almost always saves money.

Roger

Thank you @nymedic - it's my pleasure to hear that you love your System 2000!

Turning on SmartBoost will definitely help reduce recovery time to recover from setback. If you look at heat output from baseboard, an increase in hydronic temperature of 30°F can boost baseboard output by about 40%.

From an efficiency standpoint, there is virtually no change in efficiency on the non-condensing System 2000 running with SmartBoost on or off. If you want a bit faster recovery, set SmartBoost for 25 minute delay as it will kick in 20 minutes sooner than the 45 minute delay. Please make sure your baseboard is clean, louvers are open, and no furniture or heavy carpeting or pads are blocking the front - this is actually quite common.

Here's why from a technical standpoint: You can estimate the efficiency difference with the burner running by looking at a combustion efficiency chart. 30°F higher boiler temps yield somewhere around 30°F higher stack temperatures or only about ¾% lower combustion efficiency. Because of the low mass and thermal purge design, System 2000 runs at very close to peak efficiency and oversizing has virtually no impact.

Best,
Roger

nymedic

Thanks a bunch Roger. Appreciate the feedback. Unbelievable customer service!

Erin Holohan Haskell

nymedic said:

Thanks a bunch Roger. Appreciate the feedback. Unbelievable customer service!

It sure is! Thanks, @Roger.

Roger

You’re welcome - HeatingHelp should definitely be up for the most positive forum of the web award!

Harvey Ramer

When it comes to Energy Kinetics, the people and the products they sell, are nothing short of amazing!
My customers love their yellow boilers!

Roger

Thank you, Harvey - we also take great pride in working with heating professionals like you that make up such an outstanding and dedicated group of Energy Kinetics dealers.