Hydronic Controls - Boiler with Geothermal backup?

[AlexNGreen]

We're in the process of redesigning and automating the heating system in our recently acquired house. My "early adopter" father in law built and designed the house in 1996 and has assembled a semi-automatic heating system that we would like to update.

In my searches I find many control systems that offer geothermal with boiler backup but cannot find anything that is boiler with geothermal backup?

Currently we are using a wood boiler as the primary source and ground water heat pumps as backup if we are away or if the temp drops unexpected. We have a mix of radiators and in-floor radiant heating. There are a total of 9 different zones that we would like to control and internet connectivity would be fantastic.

Any help would be great.

 

[Sokoloff]

One thing that would help is to specify what your goals are for wood with geothermal backup to get better advice.

Geothermal feeding floor radiant heat is very comfortable and cost efficient to operate, so perhaps you could consider it your primary is what I’m getting at. (It’s less effective with radiators due to the higher temps they “want” to operate at.)

 

[AlexNGreen]

Good point.

The goal is to completely automate the system and bring it up a modern state of control and still maintain the primary use of the wood boiler.

The 2 geothermal heat pumps have no problem heating the whole system and keeping things comfortable but they are a bit costly to run compare to the "free" nature of wood fuel.

The basement level is heated with floor radiant heat and is having radiators added to rooms for better temperature control.

We use the boiler when we are home and as the main source with the geothermal coming on to maintain a low temp.

The second level is currently radiators only.

What we would like is a automated system with all the sensor, zone controls, wireless thermostats, and internet connectivity.

 

[fitter30]

You could have a system that the geo systems use wifi t stats with temp sensor on wood boiler to lock out the geo's. But if you want to control everything your going to need a control or a mechanical contractor that can write code and reps a control line. Retrofitting older equipment will not be cheap.

 

[jkeyser14]

My geothermal system costs ~$2-3 per day to run. Are you sure the hassle and mess of splitting wood and feeding the boiler is worth it?

 

[AlexNGreen]

My geothermal system costs ~$2-3 per day to run. Are you sure the hassle and mess of splitting wood and feeding the boiler is worth it?

There are two answers to that.

1- We have an unlimited supply of wood and use the cutting of wood for land management. It is a huge amount of time gone and given the choice I would rather not do it.

2- The current geothermal system was installed during the building of the house in the mid 90's. I think that a combination of lacking controls and an older system has made achieving high efficiency impossible. If we can get things controlled new geothermal heat pumps will probably be the next step.

The house currently has the boiler and geothermal so it would behoove us to keep both in place for the time being. Things will probably change in the future but we're just working with what we have.

As a side note; the house is located in central Minnesota. Winter temps can be brutal.

 

[Kaizen]

Wouldn’t just have geo on own thermostat set at whatever work?


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[AlexNGreen]

Wouldn’t just have geo on own thermostat set at whatever work?


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That would work but I was really looking for a single solution that incorporated everything into one tidy package.

Right now I'm thinking of trying out the Honeywell TrueZONE 432 panel. It seems to have most of the features that I need and its not a huge loss if it doesn't work.

https://www.supplyhouse.com/Honeywell-HZ432-TrueZONE-HZ432-Panel-11487000-p

 

[Kaizen]

That would work but I was really looking for a single solution that incorporated everything into one tidy package.



Right now I'm thinking of trying out the Honeywell TrueZONE 432 panel. It seems to have most of the features that I need and its not a huge loss if it doesn't work.



https://www.supplyhouse.com/Honeywell-HZ432-TrueZONE-HZ432-Panel-11487000-p

No this would be two part solution. So wood fired boiler runs as it should. If it fails and temp drops to fifty then geo system kicks in off the second thermostat. Only issue might be if they both use the same air delivery or hydronic radiators


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[AlexNGreen]

No this would be two part solution. So wood fired boiler runs as it should. If it fails and temp drops to fifty then geo system kicks in off the second thermostat. Only issue might be if they both use the same air delivery or hydronic radiators


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They do use the same hydronic radiators. The system is radiant in floor for the basement and cast iron radiators for the first floor. After looking into the plumbing there is a lot that needs to be corrected and added. Currently there is no temperature regulation between the two different heat delivery methods and a lack of pumps to move water through the different loops without running all loops.

I've got a lot of work ahead of me to straighten the system out and bring it up to modern standards. Certainly doable just need to find the right controls to compliment the complexity.

 

[yeldogt]

I would look at the wood side first .. see how people control them.

A wood boiler can have outdoor reset -- controlling the incoming water to the system. Typically based on the highest heat radiators.. This can be further modified down tot he floors and slab.

The typical boiler system referenced in common systems is not wood. They work off an either or .. based on cost of fuel at the moment or in the case of HP/Geo ... capacity. Blending the two is going to be problematic.

Is it using panel radiators ? Do they have individual controls using a bypass?

 

[HoosierBuddy]

This may go without saying, but you should also insure that your geothermal system is operating properly if you are going to continue to use it.

I've heard of many of those old systems that have had problems and reverted to backup "emergency" heat mode...which is just resistance-electric. Likely results in 5 times as much electricity being used.

Not sure if that applies to your unit or not.

New pastor at a church we attend bought his first house and then was asking me "how does everyone afford these $900 power bills in the winter?" I did a double take and told him he'd better get his heat pump serviced. Sure enough...it was on the fritz and running on the resistance elements full bore. Seems like they should have a bell that starts to ding after 24 hours or something. Sure someone with some knowledge and experience is going to pick up on the fact the pump isn't running pretty quick...but your average consumer won't figure it out until they get their first power bill and maybe even not then.

Phil

 

[Jackfre]

We have a member here named "Badger..." who I believe is from your area. He's a hand and would be worth trying to contact. He's gone dark here the past year or so, but the man knows his business. On the geo unit, after 20 yrs, I would suggest for budget purposes that you look into a new unit. Fitter is correct on cost of controls that may be somewhat offset by going to a newer unit. Rather than burning the wood, why not sell it?

 

[86turbodsl]

We're in the process of redesigning and automating the heating system in our recently acquired house. My "early adopter" father in law built and designed the house in 1996 and has assembled a semi-automatic heating system that we would like to update.

In my searches I find many control systems that offer geothermal with boiler backup but cannot find anything that is boiler with geothermal backup?

Currently we are using a wood boiler as the primary source and ground water heat pumps as backup if we are away or if the temp drops unexpected. We have a mix of radiators and in-floor radiant heating. There are a total of 9 different zones that we would like to control and internet connectivity would be fantastic.

Any help would be great.

You're doing exactly what i did in my house. Geothermal/infloor with boiler backup. Propane, but the concept is almost the same. I couldn't find controls to do what i wanted, so i built my own controls using a PLC, wrote my own ladder logic. It was a learning experience. I implemented outdoor reset on both heating and cooling. Keeping the delta T down on the geothermal was my primary goal to boost efficiency. I think it's best to think of the system as a bunch of little modules that work together to achieve small goals rather than think of it as one giant monolithic program. It's easier that way.