[mk e]

It was 10F outside this morning....and with the thermostat inside set to 72 I think I about found the limit of the new heat pumps. Upstairs was right at temp with the unit running in high speed, downstairs however was trying to recover from the over night 62F....and after 2 hours of trying had only made it to 68F (I had the aux heat breaker shut off so I could see what the heatpumps could do), 15-20 minutes witht he aux heat switched back on and it was at 72 and the heat pump has kepted up with no more need for the aux heat. Becasue they are geo heapupms they are running at the same efficieny when it's 10F or 50F outside, I just found the limit of how much heat they can make.

One think I'm trying to figure out is exactly how the thermostat call for what stage of heat.....there is nothing I can find in the instructions to tell me. It looks fancier than just 1* turns on 1 stage, 2* the second, ect....It looks like it remembers what was on last time and also times the heat call to know it'sa not making progess and needs the 2nd stage. I think it doesn't call the aux heat on a recovery cycle (going from night to day setting) until the time passes when it's supposed to be at temp (it trys to have the temp to the set point at the set time rather than start heating at the set time. It's also got a hook-up for an outside temp probe....that I think it uses the info to help decide when to start a recovery cycle. It's doing a lot of thinking....I just wish I knew about what.

[VRC]

Mark
Our water heater has been at 115 deg. for 5 years.Tracy is fine with it and I have to add a touch of cold or its to hot for me in the shower. Now get back to work on the car.
Vic

[mk e]

Originally Posted by VRC

Mark
Our water heater has been at 115 deg. for 5 years.Tracy is fine with it and I have to add a touch of cold or its to hot for me in the shower. Now get back to work on the car.
Vic

Thanks. Ours won't run right at 115F because "cold" water feed is actually warm from the geo tank. I finally got a response from the water heater tech guys and they say...make sure the set point is at least 20F above the incoming water temp and they recomend using a mixing valve. To me it seems like adding a mixing valve to intentionally not use all the geo water I have is a bit silly....I need to think about it a bit but it seems to be working right with the 120F set point and the geo water is about the hotest it wil ever be right now I'd think since the ehat-pumps are running full blast to deal with the 0F outside temp we have at the moment.

I'm not really happy about the kitchen sink water though I don't think....there seems to be a lot of time that cold comes out when I'm asking for hot. I guess in the kitchen the water goes on and off and runs low and that just confuses the heater so we get slugs of cold moving though the pipes. I may through a small electric unit of some kind under the sink.


I should be mostly back on the car this week, I just have to get the old furnaces out of the shop area so I can work on the car.

[mk e]

Originally Posted by mk e

One think I'm trying to figure out is exactly how the thermostat call for what stage of heat.....there is nothing I can find in the instructions to tell me. It looks fancier than just 1* turns on 1 stage, 2* the second, ect....It looks like it remembers what was on last time and also times the heat call to know it'sa not making progess and needs the 2nd stage. I think it doesn't call the aux heat on a recovery cycle (going from night to day setting) until the time passes when it's supposed to be at temp (it trys to have the temp to the set point at the set time rather than start heating at the set time. It's also got a hook-up for an outside temp probe....that I think it uses the info to help decide when to start a recovery cycle. It's doing a lot of thinking....I just wish I knew about what.

I think I’ve got the thermostat figured out and it’s pretty fancy. It understands I want the aux heat to run only when absolutely necessary so when it’s in recovery going from night to day setting it does not run the aux heat. Then it will use the aux heat to get to within 2 degrees of the set point then drop it out and try to get the rest of the way with just the heat pump….makes 2 attempts like this then on the 3rd attempt it uses the aux heat to get all the way to the set point. It basically does the same think with the 1st and 2nd stage heat pump too so it will leave the 1st stage running all the time and cycle the 2nd stage in and out to maintain temp and if that doesn’t work it leave the heatpump on high and cycles aux heat in and out to maintain temp.

Very fancy….older units use to be 1st stage within 1*, 2nd stage at 2* and 3rd stage at 38 or something like that so you never really had the house at the temp you asked for….but that was then with basic mechanical controls and today we have microprocessors it seems.

[tknobby]

Originally Posted by mk e

It was 10F outside this morning....and with the thermostat inside set to 72 I think I about found the limit of the new heat pumps. Upstairs was right at temp with the unit running in high speed, downstairs however was trying to recover from the over night 62F....and after 2 hours of trying had only made it to 68F (I had the aux heat breaker shut off so I could see what the heatpumps could do), 15-20 minutes witht he aux heat switched back on and it was at 72 and the heat pump has kepted up with no more need for the aux heat. Becasue they are geo heapupms they are running at the same efficieny when it's 10F or 50F outside, I just found the limit of how much heat they can make.

One think I'm trying to figure out is exactly how the thermostat call for what stage of heat.....there is nothing I can find in the instructions to tell me. It looks fancier than just 1* turns on 1 stage, 2* the second, ect....It looks like it remembers what was on last time and also times the heat call to know it'sa not making progess and needs the 2nd stage. I think it doesn't call the aux heat on a recovery cycle (going from night to day setting) until the time passes when it's supposed to be at temp (it trys to have the temp to the set point at the set time rather than start heating at the set time. It's also got a hook-up for an outside temp probe....that I think it uses the info to help decide when to start a recovery cycle. It's doing a lot of thinking....I just wish I knew about what.

Mark,

With the system running aux. heat, high speed, etc, do you think it is still going to be more efficient than your previous system?

Tom...

[mk e]

Originally Posted by tknobby

Mark,

With the system running aux. heat, high speed, etc, do you think it is still going to be more efficient than your previous system?

Tom...

Cost to operate wise it will be WAY cheaper than the old system.

With the units running on low speed they have a COP of 4.5-5.0 depending on ground loop temp, mine should be right around 4.6-4.7. COP is Coefficient Of Performance and a COP of 4.5 means that for every kW of electricity that goes in, 4.5 KW of heat comes out. This can be true because a heat pump isn’t making heat, it’s moving heat.

When the heatpumps go to high speed they have a COP in the 4.0-4.5 range depending on loop temp, mine are around 4.1-4.2 (you need to run a ground water set-up where you take well water and dump it to it the high end, a loop of any kind won’t get you there). Still pretty good.

For Aux heat I’m running plain old straight resistive electric so the COP is 1 so it expensive, but that is only a small part of the total heat the unit is putting normally. The heat pumps are always running and producing everything they can, and the aux heat is just a supplement that is needed when the night time temp drops below about 5F or day time temp below say -5F/-15F or so (the sun adds a lot of heat during the day) which at most only happens a hand full of days a year. If the aux and heatpump are both running the combined COP is about 2 and anytime the aux cycles off the COP goes back above 4.

I replaced a propane furnace. Where I live propane costs nearly the same as straight electric so I should cut my heating bill by about 75%. My AC costs should be about ½ what they where.

[tknobby]

Originally Posted by mk e

Cost to operate wise it will be WAY cheaper than the old system.

With the units running on low speed they have a COP of 4.5-5.0 depending on ground loop temp, mine should be right around 4.6-4.7. COP is Coefficient Of Performance and a COP of 4.5 means that for every kW of electricity that goes in, 4.5 KW of heat comes out. This can be true because a heat pump isn’t making heat, it’s moving heat.

When the heatpumps go to high speed they have a COP in the 4.0-4.5 range depending on loop temp, mine are around 4.1-4.2 (you need to run a ground water set-up where you take well water and dump it to it the high end, a loop of any kind won’t get you there). Still pretty good.

For Aux heat I’m running plain old straight resistive electric so the COP is 1 so it expensive, but that is only a small part of the total heat the unit is putting normally. The heat pumps are always running and producing everything they can, and the aux heat is just a supplement that is needed when the night time temp drops below about 5F or day time temp below say -5F/-15F or so (the sun adds a lot of heat during the day) which at most only happens a hand full of days a year. If the aux and heatpump are both running the combined COP is about 2 and anytime the aux cycles off the COP goes back above 4.

I replaced a propane furnace. Where I live propane costs nearly the same as straight electric so I should cut my heating bill by about 75%. My AC costs should be about ½ what they where.

That's impressive Mark. Thanks for the efficiency explanation.

Tom...

[KKRace]

This has me thinking now. The neighbors behind me all have abandoned wells since the county ran water and sewer. I wonder if I could trench over and try to purchase an easment to use their unused wells for a Geo thermal install?

What are the downsides of the vertical bores?

[mk e]

Originally Posted by KKRace

This has me thinking now. The neighbors behind me all have abandoned wells since the county ran water and sewer. I wonder if I could trench over and try to purchase an easment to use their unused wells for a Geo thermal install?

What are the downsides of the vertical bores?

In theory you could do that, in practice though.....people don't like to hand out easements as a rule. Also, are the wells still useable? Around here they require you to hire a licensed well contractor to fill your abandon well with cement and get very very angry when you don't.

All that aside, vertical bores are probably better than what I did but are more expensive which leads to drilling shallower wells which leads to less efficient, but done correctly it's better. The ground temp isn't truly stable until you get down 30 feet or more, and that says wells are the best. I'm at about 7 feet deep so the ground temp is +/- about 7-8F.

From what I've read you need about 150 feet of well for every ton of system capacity and the wells need to be spaced about 20 feet apart to make it work the way it's supposed to work.

I just got my first electric bill that had the geo on for about 18 days including near record cold for about 1 week and it looks like it added about $110 so a full month of heat mid winter should be about $185 vs about $750+ of propane, so about 1/4 the cost just like the math said, not bad (remembert the COP is 4-4.5 or 4+ units of heat for every unit of electric purchased and propane costs nearly as much per unit heat as straight electric...and that is where the 1/4 cost comes from) . I'm expecting it will cut my AC bills in 1/2 as well becasue the new COP is 5 for AC vs 2.5 on my old system.

[cribbj]

Originally Posted by mk e

From what I've read you need about 150 feet of well for every ton of system capacity and the wells need to be spaced about 20 feet apart to make it work the way it's supposed to work.

The geo contractors here in Houston were doing vertical boreholes on 20 ft spacings initially, but found they lost efficiency at the peak of the cooling season because the earth became "saturated".

As a result, the owners were forced to add supplemental conventional A/C capacity - not the kind of news you welcome after funding a system that already cost 3x more than conventional (note, this was 10 years ago - so maybe prices have balanced out) I think the local contractors are now using 30 or possibly even 50 foot spacings for shallow boreholes.

Most of these were new construction cases, so the homes were fairly well insulated - not like the uninsulated crackerboxes that were built around here in the 70's and 80's.

[mk e]

Originally Posted by cribbj

The geo contractors here in Houston were doing vertical boreholes on 20 ft spacings initially, but found they lost efficiency at the peak of the cooling season because the earth became "saturated".

As a result, the owners were forced to add supplemental conventional A/C capacity - not the kind of news you welcome after funding a system that already cost 3x more than conventional (note, this was 10 years ago - so maybe prices have balanced out) I think the local contractors are now using 30 or possibly even 50 foot spacings for shallow boreholes.

Most of these were new construction cases, so the homes were fairly well insulated - not like the uninsulated crackerboxes that were built around here in the 70's and 80's.

I remember you mentioning something about that.

It's one of those things where dirt is not dirt I think. On a big commercial install they'd call in a geologic engineer of similar to test the soil conductivity and go from there but on residential jobs normally they go by estimates and try to be a bit conservative (ie when in doubt use more space or deeper wells ect).

Here we have good moisture content in the soil so it conducts pretty well and wells or trenches (for coils like I used) can be 10ft on centers apart (I used 10ft) with no issues...but dry soil and the number can be very different. I guess the key is to do some research about what's been done successfully in your area before rather than just go by a rule of thumb you heard or read somewhere.

[KKRace]

Originally Posted by mk e

In theory you could do that, in practice though.....people don't like to hand out easements as a rule. Also, are the wells still useable? Around here they require you to hire a licensed well contractor to fill your abandon well with cement and get very very angry when you don't.

Here they let us keep one outside spigot from the well for car washing and watering lawn.

[mk e]

Originally Posted by cribbj

The geo contractors here in Houston were doing vertical boreholes on 20 ft spacings initially, but found they lost efficiency at the peak of the cooling season because the earth became "saturated".

As a result, the owners were forced to add supplemental conventional A/C capacity - not the kind of news you welcome after funding a system that already cost 3x more than conventional (note, this was 10 years ago - so maybe prices have balanced out) I think the local contractors are now using 30 or possibly even 50 foot spacings for shallow boreholes.

Most of these were new construction cases, so the homes were fairly well insulated - not like the uninsulated crackerboxes that were built around here in the 70's and 80's.

The more I think about this the more something doesn't sound quite right. If you are talking about big houses then you are talking about multiple wells 2, 3, 4 maybe (they go about 3 tons per well around here) so if the spacing was wrong you'd only need to re-drill 1 or maybe 2 which isn't all that more much money and everyone would be happy again....no it sounds more like the entire system was undersized so there was basically everything would need replacing and the well spacing was a cover story to avoid a really big liability issue....maybe

[cribbj]

Originally Posted by mk e

The more I think about this the more something doesn't sound quite right. If you are talking about big houses then you are talking about multiple wells 2, 3, 4 maybe (they go about 3 tons per well around here) so if the spacing was wrong you'd only need to re-drill 1 or maybe 2 which isn't all that more much money and everyone would be happy again....no it sounds more like the entire system was undersized so there was basically everything would need replacing and the well spacing was a cover story to avoid a really big liability issue....maybe

Mark, you may well be right; scams & coverups of shoddy work are just a way of life in the Houston area. Perhaps the boreholes simply weren't drilled deeply enough, or there weren't enough of them to handle the total tonnage. I'll do some asking around and see what people are using these days, although geo really hasn't taken off around here the way it should have. We have huge cooling and dehumidification needs, but very little heating load.

[KKRace]

Do they use the vertical bores to do a water to water heat exchange or do you have to grout the bores and just do a heat to dirt exchange like a horizontal system?

I was thinking with access to two wells, pump water from one and drain it back into the other?

[mk e]

Originally Posted by KKRace

Do they use the vertical bores to do a water to water heat exchange or do you have to grout the bores and just do a heat to dirt exchange like a horizontal system?

I was thinking with access to two wells, pump water from one and drain it back into the other?

Normally you have to grout a U tube of pipe into the well.....I don't know is you are allowed to pump water back into the gound anywhere, certainly its not allowed where I am and it's pretty rual here.

[champagne612]

I am wrapping up my Geo Thermal installation.

58 Tons of underground and 38 tons of HVAC units.

It's had a few issues and without the tax credits I would pause spending the additional cost.

I went with large pumps in the main house one is a spare .. just in case one blows. The motors are all 3 phase which were a pain in my wallet from the local electrical utility company to bring in 3 phase. The pumps are also very loud!

My guess is the bills are 1/3 but the installation costs with the tax credit make the project a 10 year plus pay back.

Also installed pipes under the drive and walks. Apparently there is a broken line so I am debating on putting it off for a bit.

[mk e]

Originally Posted by champagne612

I am wrapping up my Geo Thermal installation.

58 Tons of underground and 38 tons of HVAC units.

That is MASSIVE......so I'm guessing so is the hose it's attached to

Also installed pipes under the drive and walks. Apparently there is a broken line so I am debating on putting it off for a bit.

That's on my wish list as is adding the garage to the system....but that needs to wait until the next time I need to do work on them I guess as tearing up good stuff just doesn't make a lot of sense.

[champagne612]

Originally Posted by mk e

That is MASSIVE......so I'm guessing so is the hose it's attached to




That's on my wish list as is adding the garage to the system....but that needs to wait until the next time I need to do work on them I guess as tearing up good stuff just doesn't make a lot of sense.

Here are my massive motors in the main house - gravity is overrated feel free to rotate this

It was a 18 year renovation project which I took over 9 months ago - the guy added 10,000+ sf onto a 100 yr old historic home.

[wetpet]

What's the gph on those things? or is it mainly the head pressure?