Froling Add-on Install

[warno]

2 questions. I think one was answered already if so I apologize.

What is the need for the opposing inline check valves and the swing check just down the line?

What is your heat exchanger from? Is it a home made unit?

Install looks good by the way.

 

[nhtreehouse]

I feel like this is getting drawn out now lol. I'm ready for this to be over.

I can almost count the remaining solder joints with my fingers... and toes.

Boy do I ever know that feeling! Keep at it - believe me, it's way worth it in the end! I went with the "just get it operational, optimize later" approach. First fire for the Froling was 1/16/18, and I didn't have any insulation on the tank at the time. In fact, I was putting insulation on as the boiler was first charging the tank! Still taking care of little odds and ends, but having the boiler up and running is pretty awesome. Keep going!

 

[Fred61]

I see you have both swing checks and spring checks in the photo. Which ones do you have the most faith in?

 

[Marshy]

2 questions. I think one was answered already if so I apologize.

What is the need for the opposing inline check valves and the swing check just down the line?

What is your heat exchanger from? Is it a home made unit?

Install looks good by the way.

It's all good. I am using an unpressurized thermal storage bank which has a drop in copper coil heat exchanger. It hangs in the side of my square tank. The reversed spring checks allow the system to add heat to the storage bank and remove it using the same htx. The flow is reversed to maximize the thermal differential. Heating the tank you want hot water to enter the htx at the surface of the tank where it is the warmest and travel to the bottom of the htx. When withdrawing heat the water enters from the bottom of the htx and travels upwards.
When a house zonen calls for heat and the boiker is running it will satisfy the house load directly then go back to adding heat to the storage. All other times no fire in the boiler the house demand will use run through the heat bank.
See pic attached.

I see you have both swing checks and spring checks in the photo. Which ones do you have the most faith in?

Probably the swing checks.
Why do you say that? Please share your experience.
Tram provided the plumbing schematic and calls for regular swing checks in some areas and weighted swing checks in others. I could not find a weighted swing check so I talked with then about using spring instead.

 

[warno]

that's actually a good idea. Very nice.

 

[Fred61]

I asked about the check valves because I too have a mix but only a total of 4 consisting of 2 swing checks, 1 weighted check and one spring check.

Forgetting the weighted check because it has never had issues brings the discussion to the two swings and the one spring check.
Over the years I have had three swing checks occasionally stick open and allow backflow. After freeing them up several times I opted to replace one of them with a spring check. I still periodically have trouble with the swing checks but have not had a problem with the spring check.

I went by "seat of the pants" engineering when choosing the opening pressure. Been so long ago now I forget what I chose. I would need to check my file.

 

[Marshy]

I asked about the check valves because I too have a mix but only a total of 4 consisting of 2 swing checks, 1 weighted check and one spring check.

Forgetting the weighted check because it has never had issues brings the discussion to the two swings and the one spring check.
Over the years I have had three swing checks occasionally stick open and allow backflow. After freeing them up several times I opted to replace one of them with a spring check. I still periodically have trouble with the swing checks but have not had a problem with the spring check.

I went by "seat of the pants" engineering when choosing the opening pressure. Been so long ago now I forget what I chose. I would need to check my file.

I only have two swing checks in the system. Hopefully they are reliable and I never have replace them. I hope that's true for all of them for that matter. I may just add another union because of this conversation though.

 

[maple1]

It's all good. I am using an unpressurized thermal storage bank which has a drop in copper coil heat exchanger. It hangs in the side of my square tank. The reversed spring checks allow the system to add heat to the storage bank and remove it using the same htx. The flow is reversed to maximize the thermal differential. Heating the tank you want hot water to enter the htx at the surface of the tank where it is the warmest and travel to the bottom of the htx. When withdrawing heat the water enters from the bottom of the htx and travels upwards.
When a house zonen calls for heat and the boiker is running it will satisfy the house load directly then go back to adding heat to the storage. All other times no fire in the boiler the house demand will use run through the heat bank.

I'm a but unfamiliar with this kind of setup, but can the system flow water both ways at the same time? I.e., when burning, can the boiler send water to both the house and storage? Or is it one or the other? Thinking both but the way you worded it sounded like one or the other - and I don't have the head space at the moment to try to figure it out for myself.

 

[Marshy]

I'm a but unfamiliar with this kind of setup, but can the system flow water both ways at the same time? I.e., when burning, can the boiler send water to both the house and storage? Or is it one or the other? Thinking both but the way you worded it sounded like one or the other - and I don't have the head space at the moment to try to figure it out for myself.

One or the other only. The boiler controls decide where to send hot water when the fire is burning and house demands take priority. Flow is controlled through zone valve ZV-1. When it's closed heat goes to storage. When it's open it goes to house.

 

[maple1]

Hmm, OK. Interesting. You're on another level from me, with the Froling & how smart it is and how capable it can control things. Plus the different means & methods of the storage side. I know that if my boiler was sending all its output to the house on a call for heat, it would be heating up fairly quickly and idling if it could idle - it can make a lot more heat when it's burning than the house can distribute.

Looking forward to seeing some performance reports.

 

[Fred61]

- it can make a lot more heat when it's burning than the house can distribute.

Same with mine. Never been a problem distributing from storage. When whole house is calling, storage temperature rises slowly during daily burn.

 

[Marshy]

Your not getting the whole explination from what little I've shared. TV-2 Is a tempering valve and if the water returning from the zones is above 160-165F a flow returning from the zones is shunted back to circulator C1 to give up more heat to the zones. If C1 is directing all flow back to circulator C1 and the boiler is burning the boiler flow from C3 will be going to the htx as there is no flow path down stream of ZV1, just a circulating loop. Once the return water from the zones is below 160F TV-2 redirects the water back to get heated. When that happens the water from the boiler is directed to the zones because there is now a flow path that is completed.

TV2 and TV1 are thermostatic valves. TV1 is min return protection to keep return water above 140F. Clear as mud?

The controls are set to provide priority to the zone any time they aree calling for deman. That does not mean all the boiler output is directed to the zone, just that it will receive it's heat from the boiler (while firing) and any additional flow not being consumed by the zone in demand will go to the tank similtaniously. That's my understanding.

 

[maple1]

Think I got you now - and maybe it can go both ways at the same time when burning, depending simply on how much diverting TV2 is doing while ZV1 is open & house is heating?

Was also wondering after looking closer what prevents ghost flow through the boiler when it isn't burning - or maybe TV1 would prevent that?

Sounds like you have things well sorted.

 

[Marshy]

Think I got you now - and maybe it can go both ways at the same time when burning, depending simply on how much diverting TV2 is doing while ZV1 is open & house is heating?

Was also wondering after looking closer what prevents ghost flow through the boiler when it isn't burning - or maybe TV1 would prevent that?

Sounds like you have things well sorted.

Yes, its possible the c3 flow out of the boiler is split between the tank and the zones if TV2 is in some intermediate position...

Regarding the ghost flow through the boiler... I don't know how susceptible it is. I believe that is why they want a weighted check on the oil boiler outlet so there is some restriction to prevent flow through it.

 

[maple1]

Would likely be something to watch for once you're up & going. Mine would pull some flow through the cold boiler, sometimes, until I swapped my 15-58 load circ to an Alpha which runs slower flows. Which told me that my loading unit wasn't doing much to prevent that, but your TV1 might be more help than it is. I kind of also made things up as I went along, you're ahead of me there too.

 

[Marshy]

I tried to build it as close to the print ad I could. There are some differences that I won't go into (for time sake) but I believe the system will operate as intended. Once operational I'll use my FLIR gun to verify no ghost flow. Worst case is I have to install another zone valve at the oil boiler inlet. The issue is the ones I looked at were only 1", none were 1.25" so it's a fairly good restriction. Maybe it's not a big deal idk.

 

[Marshy]

Since I'm on the subject and have the floor so to speak....

I was going to have the C1 circulator discharge piping go to the opposite side of the expansion tank so that way the flow will pass through this air scoop also. I will move the check valve accordingly so it doesn't backflow into the oil boiler either. Thoughts?

See in purple.

 

[BoiledOver]

Is their a reason for not using two coils in the tank? One for charging and one for heating demands.

 

[Marshy]

Is their a reason for not using two coils in the tank? One for charging and one for heating demands.

There is no need for two.

 

[Chris Hoskin]

Your not getting the whole explination from what little I've shared. TV-2 Is a tempering valve and if the water returning from the zones is above 160-165F a flow returning from the zones is shunted back to circulator C1 to give up more heat to the zones. If C1 is directing all flow back to circulator C1 and the boiler is burning the boiler flow from C3 will be going to the htx as there is no flow path down stream of ZV1, just a circulating loop. Once the return water from the zones is below 160F TV-2 redirects the water back to get heated. When that happens the water from the boiler is directed to the zones because there is now a flow path that is completed.

TV2 and TV1 are thermostatic valves. TV1 is min return protection to keep return water above 140F. Clear as mud?

The controls are set to provide priority to the zone any time they aree calling for deman. That does not mean all the boiler output is directed to the zone, just that it will receive it's heat from the boiler (while firing) and any additional flow not being consumed by the zone in demand will go to the tank similtaniously. That's my understanding.

Good description.

 

[Chris Hoskin]

Is their a reason for not using two coils in the tank? One for charging and one for heating demands.

Two reasons: first, cost. With one coil doing both input and output duty, you only have to buy one coil. Copper ain't cheap. Second, if you have one input coil and a separate output coil, you have to wait to have heat in the tank before you can get heat to the house. The STSS-style drawing shared above allows you to send heat straight to the zones with only "extra" heat (that the house isn't using) going to the tank. A two-coil system is probably simpler and the delay in getting heat to the zones is probably not a big deal if you have a low temp heating system ( a bigger deal if you have hot water baseboard and a standard indirect water heater).

 

[Chris Hoskin]

Hmm, OK. Interesting. You're on another level from me, with the Froling & how smart it is and how capable it can control things. Plus the different means & methods of the storage side. I know that if my boiler was sending all its output to the house on a call for heat, it would be heating up fairly quickly and idling if it could idle - it can make a lot more heat when it's burning than the house can distribute.

Looking forward to seeing some performance reports.

The Fröling is a smart boiler to be sure, but this set up is not controlled by the wood boiler works with any boiler - this is a plumbing schematic we have used for 15+ years. The key is the two thermostatic valves and our BLT Control controlling C1 circulator, ZV1 zone valve and the back-up boiler.

 

[Chris Hoskin]

I feel like this is getting drawn out now lol. I'm ready for this to be over.

I can almost count the remaining solder joints with my fingers... and toes.

HTX is pipe tight. Only thing left on this side of the system is the gravity dump zone. It's ready to hang overhead.
View attachment 222875

Other side of the wall looks like this. View attachment 222876
I'm about 5' short on copper tubing to finish it out. Still have 20 joints to do on this side (or a few more).

Hi Marshy, is this picture showing pipe BEFORE it's been soldered? Looks like you've got port one of TV2 plumbed into the left of C1?

 

[BoiledOver]

Two reasons: first, cost. With one coil doing both input and output duty, you only have to buy one coil. Copper ain't cheap. Second, if you have one input coil and a separate output coil, you have to wait to have heat in the tank before you can get heat to the house. The STSS-style drawing shared above allows you to send heat straight to the zones with only "extra" heat (that the house isn't using) going to the tank. A two-coil system is probably simpler and the delay in getting heat to the zones is probably not a big deal if you have a low temp heating system ( a bigger deal if you have hot water baseboard and a standard indirect water heater).

Thank you for addressing my question. Obviously this is a proven system design or you wouldn't suggest it. To my simple mind I would think the cost difference to pretty much a wash, just a guess at this point. In the posted images there are quite a few components that could be eliminated with a two coil setup, components that may need service or replacement at some point. Wishings of success to the new boiler operator.

 

[Marshy]

Hi Marshy, is this picture showing pipe BEFORE it's been soldered? Looks like you've got port one of TV2 plumbed into the left of C1?

I will double check this evening but I followed the directions that came in the box with the valve. The numbers on the piping schematic don't align with the directions in the box (1, 2, 3). I'll review and post how it's installed. Rather find out now then after it's full of water.