Hi,

I live about 30 minutes north of Toronto. I just had a Geothermal system installed (Tranquility 27 - 6 ton) in a 4000+ square foot home which is R2000 (heavily insulated). The system seems to be working well so far. I had a couple of newby questions...

1) I have read a post indicating that you should not set the temperature on the thermostat lower at night. We are used to a slightly lower temperature at night. Does this reduce power consumption?

2) The installer offers a 1 year complete warranty. The equipment has a standard 10-year limited warranty on major refrigerant circuit components and a 5-year limited warranty on all remaining covered components. The web site indicates that cleaning the electrostatic filter once a month is all that's needed to keep the system in good running order. The installer offers a yearly maintenance program plus another warranty on repairs. Do these make sense? I have read a number of posts from people who have maintenance on their system and suffer problems afterwards.

Thanks.

Setbacks at night may not save money if recovery includes operating at 2nd stage, which is a bit less efficient, this assumes 2nd stage might have been avoided by not setting back. Setbacks will cost money if recovery includes running auxiliary strip heaters. I would avoid setbacks greater than 4 deg F (2 deg C)

Value of yearly maintenance depends highly on quality and breadth of maintenance activity. Good yearly maintenance would include verifying proper efficient operation - loop flows, running current, comparing them with values noted during initial startup, and resolving any performance losses. Manufacturer equipment warranty may be parts only, no labor.

Must consider also that maintenance and extended warranties are generally priced to be quite profitable - possibly much higher margins than initial system install. If I had to pick between the two, I'd favor a maintenance contract over an optional extended warranty.

Thanks for the reply. Very helpful information.

Is there a way to determine when the 2nd stage and/or auxillary heater is in use?

asking the installer if there is and what triggers them would be easiest

Thanks. There is a differential setting on the thermostat - it was initially set to 1 degree for stage 1, stage 2 and aux respectively. What would be optimal from a power usage point of view? We set the thermostat at 68 during the day and 66 at night. Should i bump up the 2nd to 2-3 degrees?

Yes the only potential downside is when you need 2nd stage to satisfy the home you will have a larger temp swing , but it will be more eff and allow you to lower and raise the temp 2 or 3 degrees without triggering 2nd stage

This leaves me wondering what my best course of action would be. I like it cold when I sleep, About 55-60 degrees. I like it warm when I get up to shower, about 72 degrees. I like it at around 68 in the evening after work.
So even though I am losing some efficiency, is it actually using more electricity overall to run the system as follows during the week:

72 7:30 am
55 8:30 am
68 5:00 pm
55 9:30 pm.

The auxillary heat definitely comes on in the morning and the evening, but usually for just one cycle (I think). In the late evening, when the system shifts to 55 degrees, nothing runs for hours as the house cools.

Also, a factor, is that I have an open loop system, so the time where the system is not running is also time where I assume the well pump is not ruinnng also.

Would I be better off leaving the house at 68 degrees 24 hours per day, and just letting cold air into the bedroom at night with the heating registers closed in my room?

If I were you, I would disable the aux heat. Our temp scheme is much the same as yours. I have disabled the aux heat and don't have to worry about it coming on. What brand is your heat pump and thermostat?

my heat pump and thermostat are both ClimateMaster.

If I disable the aux heat, is it going to heat up so slowly that I should set the warmer temps to come on earlier?

As for disabling the aux heat, can I just kill it at the breaker panel? Or should I find out how to disable it at the heat pump?

Most t-stats are equiped with adaptive intellegence , which will learn to come on earlyier to get to the right temp at the right time , not sure if they have issues with geo recovery times

Yes , it will take longer for your house to heat up.  On really cold mornings,  it might take several hours.  Depending on the balance point of your system.

One of the wires in your tstat is hooked to a "W" terminal .  This is what turns on the aux heat.  If you disconnect the wire,  aux heat will not come on.

This is where comfort has to be balanced with economy.  If you want your house to heat up fast in the mornings, don't disable aux heat.

Aux heat really spins the meter - figure it costing 3-5 times as much per btu as your geo heat pump.

why do people get aux heaters anyways? for back up? my house is 1650 sq feet upstairs and about the same in the basement, it is -35C and windy and my 3-ton has no trouble keeping up. wouldnt electric 'heat strips defeat the whole purpose of having geothermal?

Backup, for sure.

We don't include them here in Florida - loss of heat is just a nuisance. That and heat strips cause a year-round loss of 0.05-0.10 in WC blower static pressure.

Anywhere that loss of heat could cause a house to become uninhabitable and / or do $10k plus in plumbing freeze / flood damage, I'd want a back up.

At minus 35 C, loss of a compressor, loop pump, contactor, reversing valve or leak in any refrigerant component could rapidly lead to a dangerous, expensive freeze - Aux heat strips bail you out of that scenario until repairs can be made - a no brainer in my book.

So if comfort is my main concern, and total cost is my second concern, am I better off killing the heat strips and keeping the house at 68, and closing off heat to the bedroom, and bringing in cold airto cool the bedroom, or cycling like I am with the heat strips coming on as needed.
Also, I have the same need for a cold sleeping space in the summer, so am I better off keeping the whole house ACed to 72, and putting in a window unit (which costs almost double per kWh for me) or cooling the whole house down to 60 at night and letting it warm up again during the day.

I wish I could just sleep comfortably in a warmer room. That seems like the best solution, but unfortunately, I have little control over that one.

robkindovernh,

User can delay aux heat from coming on for up to 120 minutes (Climatemaster calls it Smart Heat Staging) on most Climatemaster tstats. It is available from PROGRAM SETTINGS menu. From 55 to 72 degrees, it is a long span for the heat pump to cover without electric heat. Climatemaster's programable tstats have a feature called "Smart Recovery", meant to adjust temperature gradually from a setback and reduce use of electric heat.

Regards, Masoud

One more interesting question...

In Ontario, they are moving to a variable rate for electricity. So overnight rates drop dramatically (to 4 cents/kwh). Peak periods are 8.8 cents. There are extra costs (distribution, taxes etc), this is just the per kwh rates proposed. We also have a "debt retirement cost" which translates to "you have to pay for the stupid mistakes we made 20 years ago" fee.

I was wondering if it would make sense to do the following (ignoring comfort issues for now):

- turn off aux heating via the thermostat
- set temp at night to be 3-5 degrees higher than daytime

For example, 72 degrees at night, 68 during the day with the idea that the system would be off for a portion of the day during the peak energy time.

I know the 2nd stage would engage at night, but if the relative price of electricity was 40-50% less at night, would this make any sense?

Thanks.

Yes building up the thermal mass of a space during off peak to help ride out on peak is a great idea , works even better with a multizone system allowing you to dump heat into an unused zone and runing your fan to even out on peak 
This clearly only holds true if your well insulated

My system fired up Feb 25 2007. I moved in May 2007. AC worked fanatastic during the hot days in July. I find now that I do not turn down my thermostat like I did in my old house at night as I find it takes to long to recover therefore working in stage 2 alot more and/or wanting to kick in stage 3 (electric heat). My breaker for the electric heat is turned off and has remained off, even with the large cold snap we have had here the last 3 weeks (my outside temp gauge in my truck read -40C on the way to work yesterday AM).  Right now we are -9C outside and my unit pretty much runs in the first stage. In the last  2 months I adjusted temps accordingly to see how it would affect the system and I found that leaving the thermostat at 21C is opitmal. Also, my basement and garage and a few other areas are heated with the infloor water to water unit and since my home is a bungalow with vaulted ceiling, I keep the overhead fan running about medium speed to help circulate the air.

Cheers!

Dean IN Edmonton