Controlling a Complicated HVAC Setup

[ian351c]

Hello all,

I have a pretty complicated HVAC setup at home and am hoping to gain some wisdom on how to control it via HomeSeer. First, some background: my house is very "interesting" when it comes to temperature control. The original house was built in the 1920s, 2 floors, about 1500 sq ft, with a steam boiler in the basement and radiators on both floors. In the late 90s the house was remodeled with a pretty large add on, bringing the total area to about 3500 sq ft. In the process, the steam heat was removed from the original second floor and added to a new "sun room" (enclosed prefab porch covering basically) with a new gas fired boiler and a thermostat in the sun room (for the steam). The rest of the house (original 2nd floor + addon on first and 2nd floor) has a gas furnace + A/C (aka "central heating/cooling"). The thermostat for this setup is on the second floor with a Western exposure and a large sliding glass door (it doesn't get direct sunlight, but it can get much warmer there than other parts of the house in the afternoons). The last important piece of info is that I live in Michigan, so there's that...

All of this equipment is 15-20 years old, so it won't be too long before I end up replacing most of it. In the meantime, I'd like to see what I can accomplish with HomeSeer and some ZWave gear. Using sensors, thermostats, registers, etc. can I get better and/or more efficient cooling out of my existing HVAC system or is the effort not worth the return?

Thanks!

[ServiceXp]

Hello all,

I have a pretty complicated HVAC setup at home and am hoping to gain some wisdom on how to control it via HomeSeer. First, some background: my house is very "interesting" when it comes to temperature control. The original house was built in the 1920s, 2 floors, about 1500 sq ft, with a steam boiler in the basement and radiators on both floors. In the late 90s the house was remodeled with a pretty large add on, bringing the total area to about 3500 sq ft. In the process, the steam heat was removed from the original second floor and added to a new "sun room" (enclosed prefab porch covering basically) with a new gas fired boiler and a thermostat in the sun room (for the steam). The rest of the house (original 2nd floor + addon on first and 2nd floor) has a gas furnace + A/C (aka "central heating/cooling"). The thermostat for this setup is on the second floor with a Western exposure and a large sliding glass door (it doesn't get direct sunlight, but it can get much warmer there than other parts of the house in the afternoons). The last important piece of info is that I live in Michigan, so there's that...

All of this equipment is 15-20 years old, so it won't be too long before I end up replacing most of it. In the meantime, I'd like to see what I can accomplish with HomeSeer and some ZWave gear. Using sensors, thermostats, registers, etc. can I get better and/or more efficient cooling out of my existing HVAC system or is the effort not worth the return?

Thanks!

I'll take a try at this.... I'm going to assume you meant heating and cooling?

1) I do think it's possible to improve the house heating and cooling cycle profiles, which should give you a net gain in usage efficiency. You will not however gain any mechanical efficiencies. That can really only come with equipment replacement and or duct base (or water based) zoning control.

2) You need to be VERY careful about using Z-Wave registered for zone control without properly installing and balancing a return air bypass system. Unless you have the tools, you will need to call a professional to accomplish this for you.

3) We need to know more about the boiler and the zones it handles.

a) Is the entire house fed with a gas fired steam boiler or is there another water boiler?
b) How many zones are control with zone valves?
c) Does the current ducted system utilize any zoning control?
d) What types of occupancy profiles does your family use (children, adults, work schedule, school schedule, % of house occupied on average, etc.)
e) other than "better and or more effiencent cooling" what are your other goals? (ie: the ability to control, record, measure..etc your HVAC system?)

[ian351c]

Thanks for the reply! To answer your questions:

a) The boiler serves the first floor of the original house and the add on sun room. The rest of the house is heated by a forced air gas furnace.

b) There are no "zones" as such. There is a valve on each radiator, and there are a few "valves" in the ducting that I have seen in the basement. But none of that is controlled by the thermostat(s).

c) No. (See b)

d) This is all over the place. I work from home most days but will be gone a few hours at a time. The wife is a "homemaker" (bless her, couldn't pay me enough to do what she does ) so her schedule varies as well. And the kids are school age and all the goes with that. As for occupancy, all the bedrooms are upstairs, and most of the use of the downstairs is in the "back" (west side) of the house, which are all areas controlled by the newer heating/cooling system.

e) Yes. I'm a big Cacti nerd when it comes to my home network, and I would love to track energy use, temperature, etc. in the house. And some control would be nice as well. It shouldn't be too hard to improve on my $400-600 gas+electricity bills in the winter.

[Steve Q]

There is no question that you can save money by using home automation to control your heating and AC. I also live in Michigan and have many years of experience using Homeseer to monitor and control my HVAC. The key is balancing the cost of home automation equipment versus your cost of electricity and gas and your own comfort requirements. A simple overnight setback device for your boiler will save you money. However, adding zone control to an existing house, will likely never be cost effective. You should probably use that money for a new HVAC system.

I have just installed a new geothermal HVAC system. I have 5 years of data from my old system. Over the next year, I will be comparing data from my new system to that from my old system. I hope to be able to calculate my breakeven point for the extra cost associated with geothermal. I will be posting periodically.

Steve Q


Sent from my iPad using Tapatalk HD

[ServiceXp]

Thanks for the reply! To answer your questions:

a) The boiler serves the first floor of the original house and the add on sun room. The rest of the house is heated by a forced air gas furnace.

b) There are no "zones" as such. There is a valve on each radiator, and there are a few "valves" in the ducting that I have seen in the basement. But none of that is controlled by the thermostat(s).

c) No. (See b)

d) This is all over the place. I work from home most days but will be gone a few hours at a time. The wife is a "homemaker" (bless her, couldn't pay me enough to do what she does ) so her schedule varies as well. And the kids are school age and all the goes with that. As for occupancy, all the bedrooms are upstairs, and most of the use of the downstairs is in the "back" (west side) of the house, which are all areas controlled by the newer heating/cooling system.

e) Yes. I'm a big Cacti nerd when it comes to my home network, and I would love to track energy use, temperature, etc. in the house. And some control would be nice as well. It shouldn't be too hard to improve on my $400-600 gas+electricity bills in the winter.

Ok, so installing new "controllable thermostats" will be your cheapest and easies starting solution. This should allow you to develop a base line of usage so you can try different setback profiles that suites your families comfort level.

Your answer to d is going to make if somewhat difficult to find those comfort level profiles that save you money though.. You said there are valves on each of the radiators, are they bleeders, mechanical on/off control valve, or thermostatic control valves?

Is your steam system a one pipe or two pipe?

[ian351c]

There is no question that you can save money by using home automation to control your heating and AC. I also live in Michigan and have many years of experience using Homeseer to monitor and control my HVAC. The key is balancing the cost of home automation equipment versus your cost of electricity and gas and your own comfort requirements. A simple overnight setback device for your boiler will save you money. However, adding zone control to an existing house, will likely never be cost effective. You should probably use that money for a new HVAC system.

I have just installed a new geothermal HVAC system. I have 5 years of data from my old system. Over the next year, I will be comparing data from my new system to that from my old system. I hope to be able to calculate my breakeven point for the extra cost associated with geothermal. I will be posting periodically.

Steve Q


Sent from my iPad using Tapatalk HD

That should be interesting to see! Looking forward to your posts...

[ian351c]

You said there are valves on each of the radiators, are they bleeders, mechanical on/off control valve, or thermostatic control valves?

Is your steam system a one pipe or two pipe?

There are mechanical valves on each radiator, similar to something like a hose bib that you can turn to allow or block steam from getting to the radiators (I've read that these should always be either all the way on or all they way off). There are also what I would call "relief" valves at the opposite end of where the steam comes into each radiator. So maybe that's a bleeder?

The whole system runs on a single pipe that makes a loop from the boiler, to each radiator, and back to the boiler.

Full disclosure: I live in MI, but I'm from CA so this whole radiator business is pretty new to me.

[ServiceXp]

There are mechanical valves on each radiator, similar to something like a hose bib that you can turn to allow or block steam from getting to the radiators (I've read that these should always be either all the way on or all they way off). There are also what I would call "relief" valves at the opposite end of where the steam comes into each radiator. So maybe that's a bleeder?

The whole system runs on a single pipe that makes a loop from the boiler, to each radiator, and back to the boiler.

Full disclosure: I live in MI, but I'm from CA so this whole radiator business is pretty new to me.

Those are vents...

Yeah so you pretty much need to wait until replacement time to realized big energy savings. (outside of the "non tech" standard stuff, like better windows, attic insulation, sealing up the house, etc.)

You may want to look into having an energy audit done. They will perform a blower door test on the house (among other things like thermal imaging) to see how tight the house is, and to find the air leaks.

Call your electric utility, they should be able to provide contact information to a qualified company.

[Uncle Michael]

If upfront cost were not a consideration, then I'd recommend that you undertake to upgrade your home's HVAC system ASAP. I'm guessing that isn't (or wasn't) in your plans right now, but as others have observed, there's not much you are going to be able to do with your current system to save much money other than increasing the discomfort level by keeping the house cool in the winter and warm in the summer.

I agree with the energy audit, but be sure to get one that identifies air infiltration points and areas of inadequate insulation. Addressing those will probably have the most short term impact on heat/cool expenses.

[ian351c]

Thanks everyone!

I'll definitely look into the energy audit and won't spend too much time on trying to control what I have for now.