DIY Radiant heat?

[Bone1099]

Im thinking about adding radiant heat to a few rooms in the far end of the house. Im thinking of using pex pipe pulling water from the hot water line that is already in that end of the house add all the pex radiant plumbing some sort of pump and adding a return line to to my water heater eventually I would like to add a air to water heat exchanger on top of my firepalce insert to reheat the water a bit before it returns to the water heater. can this be done pretty easily or is there a major flaw in this plan.

 

[LLigetfa]

Assuming by water heater you mean DHW as in potable water. That would require the more expensive recirc pump that's approved for potable water. I looked into using my water heater for the tile floors in the bathrooms and opted to put in electric floor heat instead.

 

[Gooserider]

Im thinking about adding radiant heat to a few rooms in the far end of the house. Im thinking of using pex pipe pulling water from the hot water line that is already in that end of the house add all the pex radiant plumbing some sort of pump and adding a return line to to my water heater eventually I would like to add a air to water heat exchanger on top of my firepalce insert to reheat the water a bit before it returns to the water heater. can this be done pretty easily or is there a major flaw in this plan.

I'm going to move this to the boiler room, as it is where more of the radiant heat people hang out...

My initial reaction is that while radiant heat is not at all a bad idea, I don't know if you are going about it in a way that will do what you want...

1. What kind of hot water line are you talking about pulling water from? Is it a line from an existing boiler, or from your Domestic Hot Water tank? If it's your DHW tank, this is generally not thought to be a great idea - for various reasons, it is generally considered best to keep heating / boiler water well separated from domestic water - codes are pretty tough on this...

2. There are a LOT of potential issues with trying to pull heat off of wood burners that weren't designed for it - ranging from potential explosion dangers, to hurting stove performance, to not so great water heating results... It can be done, but one must be VERY careful in designing such a setup, and watch out for all the various pitfalls involved - general concensus seems to be "don't do it"...

Gooserider

 

[Bone1099]

I was planning to use DHW at the bathroom near the area i plan to heat. Im thinking that if i loop this radiant system from DHW at the bathroom back into DHW supply line at water heater no chance for building pressure. What i hope to do with a heat exchanger at the fireplace insert is help the water heater not to work so hard. one reason i want to stay conected with potable water is to have instant hot water for showers and faucets. I have seen systems like this in ski homes in Brekenridge CO. Any ideas where i can find a heat exchanger capable of this? Also thinking when I do this im gonna replace all the old water plumbing. Any reason why pex wouldnt be a good idea for this

 

[Gooserider]

I was planning to use DHW at the bathroom near the area i plan to heat. Im thinking that if i loop this radiant system from DHW at the bathroom back into DHW supply line at water heater no chance for building pressure. What i hope to do with a heat exchanger at the fireplace insert is help the water heater not to work so hard. one reason i want to stay conected with potable water is to have instant hot water for showers and faucets. I have seen systems like this in ski homes in Brekenridge CO. Any ideas where i can find a heat exchanger capable of this? Also thinking when I do this im gonna replace all the old water plumbing. Any reason why pex wouldnt be a good idea for this

Replacing old plumbing with PEX is a fine idea if one was going to do so anyway. However the rest is mixed at best... Remember, TANSTAAFL, There Ain't No Such Thing As A Free Lunch... If you use the DHW line to heat the floor, you will either need to return the "used" water to the DHW heater and the water heater will have to do that much more work, or you will have some very cold showers. Likewise, any heat you get off the insert is going to be heat that you don't get into the space that the insert is warming, and or heat that was helping prevent the buildup of crud in the chimney...

Lastly ANY time you are combining water with a heating source, you need to be extremely careful about design, you can NOT rely on feeding back into the DW system as a means of pressure relief. You MUST design such that you have provisions for temp / pressure venting at the heat source, and for guaranteed ability to shed excess heat in the event of power or pump failure... Not saying it can't be done, just that it's something that must be done very cautiously.

It is worth noting that if you are dealing with domestic water pressure, you are already working with higher pressures than standard hydronic systems are designed for... A hydronic system will usually work on a maximum of 15-20 psi, with pressure valves popping at 30. A domestic water system usually runs 50-90psi. This may cause issues when picking any hydronic related components like zone valves and such.

It is also something that may be a violation of your homeowners insurance rules, and / or local building and fire codes - make sure you get approvals and such along the way as failure to do so could cause you to have severe problems if there ever was a situation that made you need to file a claim.

As to parts sources, since this is a very non-standard application, I don't know of any sources for a suitable heat exchanger, it is something you will probably need to design and build yourself. The rest of the stuff needed would be pretty standard from a component standpoing.

Gooserider

 

[Fred61]

(broken link removed to http://www.radiantcompany.com/system/open.shtml) Is a company in Barton Vt. that specializes in radiant heating sourced by DHW heaters. Their setup assures that any time domestic hot water is called for, the entire system gets flushed with incoming cold water. I have this system installed in my house and it works slick as a bean. In my case, I have replaced the large water heater with a 500 gallon unpressurised storage tank with parallel 100' coils of 3/4 inch copper. During the heating season, when I don't let the tank get below 120* I am able to take the domestic water right off the temperature control valve right into the DHW system. At other times, when I may let the tank get cold, I operate a couple ball valves and run the preheated water directly into the superstore which may be warmer than incoming cold water.
I am presently adding another zone to a new addition I constructed this summer and priced a low volume stainless circulator from them---$175.00 Not bad!
Gooserider has reservations about a system like this and also pays attention to code. A call to Radiant will answer any questions about this.
Recently, many communities have mandated sprinkler systems in any new homes (at least in this area). I have worked on several of these units and have observed two different types of installations. The higher end systems circulate all incoming water through the entire sprinkler system and the lower end systems just pressurize the sprinkler system. My choice would be to have the circulating system so If I had a fire, I wouldn't be supressing it with mold! These systems seem to be satisfying code.

 

[Paso]

I have a smaller addition on one of my shops the addition is 18 x 24 and it is heated with two electric water heaters going thru two floor loops.

The only time I need both water heaters running is when it is below - 30 otherwise the the one will maintain a nice warm floor.

I have a knock off of the Radiant system shown above. I think this is my 5th winter using this system.

 

[Gooserider]

I've heard mixed reviews on the Radiant system setups, some like them, some don't. It is also important to check your local jurisdictions for code restrictions / requirements - my understanding is that the Radiant style hybrid systems have been accepted under some of the big "model codes" but not by all local jurisdictions - Once again, MA specifically prohibits this type of install, I don't know about other places.

Radiant claims that the entire system gets flushed by incoming water, but I've heard some express doubts about this claim, especially in the case of complex systems with many parallel loops in the system. Water is "lazy" and will flow through the path of least resistance, and it seems quite reasonable to me that if one particular loop had a lower flow resistance than the others, then the bulk of the incoming water would flow through the "easy" loop, and the others would get little or no flushing.

A couple of other thoughts to keep in mind... Because the Radiant system uses potable water, you are constantly introducing O2 into the system. This will limit the types of hardware you can use in the system, both by chemistry and by codes relating to potable water. In many cases this will GREATLY increase the costs of some of the parts. For example the same size Taco pump in brass or stainless might be two or three times as much as the cast iron version... Most importantly, it will make additional complications if you were to ever want to tie any sort of standard boiler into the system.

I would also strongly reccomend using O2-Barrier PEX in the radiant parts of any system. Radiant doesn't require it, and their stuff will work with either, but if you were to ever wish to convert to a conventional boiler, you would have minimal issue if using barrier PEX, but if the system had non-barrier, you would either have to replace all of it, or get involved with either a heat exchanger or heavy duty water conditioning chemistry.

Gooserider

 

[Paso]

Sorry goose I wasn't real clear I have a modified version of what radiant system has , basic stuff is the same.

My system is closed and other than when I refill or charge the system prior to the winter season it is not connected to any potable water.

I used oxy pex everywhere except around the pump which I used copper.

I believe in our area this system wouldn't be endorsed. But it works great in my opinion.

P

 

[Gooserider]

Sorry goose I wasn't real clear I have a modified version of what radiant system has , basic stuff is the same.

My system is closed and other than when I refill or charge the system prior to the winter season it is not connected to any potable water.

I used oxy pex everywhere except around the pump which I used copper.

I believe in our area this system wouldn't be endorsed. But it works great in my opinion.

P

Don't know about the code issues, but IMHO the only significant difference between the Radiant style systems and a conventional system is the use of potable water on the heating side... They basically do the same types of things with installing the tube, (although they like to use a larger lower temp tube than some, which is not a bad idea) and so on that is not really any different than a normal boiler type install...

We tend to use boilers, not because there is anything "magic" about them, but because they are usually the optimal solution for getting as many BTU's as are needed for the least cost. However it doesn't make ANY real difference WHAT one uses for a heat source as far as the load is concerned... If the floor is getting water that's hot enough, it doesn't care how you heated the water. In the case of a smaller system, there is no reason not to use a hot water heater. It is just that in larger systems it gets marginal as to whether a DHW heater can supply enough BTU's to be effective.

Gooserider

 

[Fred61]

Radiant claims that the entire system gets flushed by incoming water, but I've heard some express doubts about this claim, especially in the case of complex systems with many parallel loops in the system. Water is "lazy" and will flow through the path of least resistance, and it seems quite reasonable to me that if one particular loop had a lower flow resistance than the others, then the bulk of the incoming water would flow through the "easy" loop, and the others would get little or no flushing.

A couple of other thoughts to keep in mind... Because the Radiant system uses potable water, you are constantly introducing O2 into the system. This will limit the types of hardware you can use in the system, both by chemistry and by codes relating to potable water. In many cases this will GREATLY increase the costs of some of the parts. For example the same size Taco pump in brass or stainless might be two or three times as much as the cast iron version... Most importantly, it will make additional complications if you were to ever want to tie any sort of standard boiler into the system.


Gooserider

If the system is balanced which is done on install and by throttling valves by temperature there is no reason the entire system will not be flushed when cold water flows through the system. To me, it's just a long pipe.

What components on the potable water side will be affected by 02? I don't know of any!

I do agree that changing to a standard system would be a problem but I let someone else worry about that. I purposely left my oil baseboard system completely separate from the wood system because of my health. When I'm gone, my wife will not be burning wood

 

[Gooserider]

Radiant claims that the entire system gets flushed by incoming water, but I've heard some express doubts about this claim, especially in the case of complex systems with many parallel loops in the system. Water is "lazy" and will flow through the path of least resistance, and it seems quite reasonable to me that if one particular loop had a lower flow resistance than the others, then the bulk of the incoming water would flow through the "easy" loop, and the others would get little or no flushing.

A couple of other thoughts to keep in mind... Because the Radiant system uses potable water, you are constantly introducing O2 into the system. This will limit the types of hardware you can use in the system, both by chemistry and by codes relating to potable water. In many cases this will GREATLY increase the costs of some of the parts. For example the same size Taco pump in brass or stainless might be two or three times as much as the cast iron version... Most importantly, it will make additional complications if you were to ever want to tie any sort of standard boiler into the system.


Gooserider

If the system is balanced which is done on install and by throttling valves by temperature there is no reason the entire system will not be flushed when cold water flows through the system. To me, it's just a long pipe.

That is what theory says, real world may not match... In addition, it assumes that you balance for equal flow on all branches, which might not be the case. It is quite likely that a person might balance for optimal heat output, which could mean more flow through some zones than others.

What components on the potable water side will be affected by 02? I don't know of any!

None, which is part of my point... The potable side MUST be designed for O2 tolerance, which requires the use of more expensive parts, and possibly limits parts choices in some cases... The actual potable system has to be this way due to the nature of it's job, but one doesn't have to tie the heating system into the potable system, and keeping them separate allows the use of less expensive non-potable-compatible, O2 sensitive parts... The point I was making is that tieing the heating system to the potable system will increase the costs of the heating system. Whether the (IMHO questionable) benefits of tieing the two together is worth it is a separate issue that each user has to decide on their own.

I do agree that changing to a standard system would be a problem but I let someone else worry about that. I purposely left my oil baseboard system completely separate from the wood system because of my health. When I'm gone, my wife will not be burning wood

I understand the logic, but don't agree with the conclusion... A heating distribution system doesn't care where it's heat comes from, and it is very easy to tie a wood burner into a fossil system in such a way that there would be little or no effort to transition from one to the other, and possibly even taking the wood system back out... Assuming the existing system works acceptably, putting in a separate redundant wood system seems to me like a serious waste of time and money. If the old system wasn't adequate, enhancing the existing system is still better as it means that both fuel burners benefit, while with a redundant setup you only gain from the enhancements when burning wood...

Gooserider

 

[Fred61]

Radiant claims that the entire system gets flushed by incoming water, but I've heard some express doubts about this claim, especially in the case of complex systems with many parallel loops in the system. Water is "lazy" and will flow through the path of least resistance, and it seems quite reasonable to me that if one particular loop had a lower flow resistance than the others, then the bulk of the incoming water would flow through the "easy" loop, and the others would get little or no flushing.

A couple of other thoughts to keep in mind... Because the Radiant system uses potable water, you are constantly introducing O2 into the system. This will limit the types of hardware you can use in the system, both by chemistry and by codes relating to potable water. In many cases this will GREATLY increase the costs of some of the parts. For example the same size Taco pump in brass or stainless might be two or three times as much as the cast iron version... Most importantly, it will make additional complications if you were to ever want to tie any sort of standard boiler into the system.


Gooserider

If the system is balanced which is done on install and by throttling valves by temperature there is no reason the entire system will not be flushed when cold water flows through the system. To me, it's just a long pipe.

That is what theory says, real world may not match... In addition, it assumes that you balance for equal flow on all branches, which might not be the case. It is quite likely that a person might balance for optimal heat output, which could mean more flow through some zones than others.

What components on the potable water side will be affected by 02? I don't know of any!

None, which is part of my point... The potable side MUST be designed for O2 tolerance, which requires the use of more expensive parts, and possibly limits parts choices in some cases... The actual potable system has to be this way due to the nature of it's job, but one doesn't have to tie the heating system into the potable system, and keeping them separate allows the use of less expensive non-potable-compatible, O2 sensitive parts... The point I was making is that tieing the heating system to the potable system will increase the costs of the heating system. Whether the (IMHO questionable) benefits of tieing the two together is worth it is a separate issue that each user has to decide on their own.

I do agree that changing to a standard system would be a problem but I let someone else worry about that. I purposely left my oil baseboard system completely separate from the wood system because of my health. When I'm gone, my wife will not be burning wood

I understand the logic, but don't agree with the conclusion... A heating distribution system doesn't care where it's heat comes from, and it is very easy to tie a wood burner into a fossil system in such a way that there would be little or no effort to transition from one to the other, and possibly even taking the wood system back out... Assuming the existing system works acceptably, putting in a separate redundant wood system seems to me like a serious waste of time and money. If the old system wasn't adequate, enhancing the existing system is still better as it means that both fuel burners benefit, while with a redundant setup you only gain from the enhancements when burning wood...

Gooserider

I spent the time and money and don't feel like I wasted anything. It works great and we're very warm and comfortable and we don't have Legionnaire's Disease. I actually have fewer controls, components (sidearms etc.) than the standard parrallel installation. If I have more flow through one loop than another, I don't care as long as I have some flow. There's plenty of flow in this house. The wife is the world leader in the use of hot water. She even brushes her teeth with hot water and leaves it running while she's brushing.
I only run the oil in the summer to heat my DHW.
You should try this type of system if you ever decide to chit can your VC Encore.
If it's so easy to install wood and oil in parallel why are there so many folks asking for help? You didn't see any posts from me asking for assistance.

 

[Gooserider]

Glad your setup works for you, which is the real bottom line on all this stuff...

I would love to dump the Encore, and have posted what I'd like to replace it with a few times... Just as a reminder see the attached... As I mentioned, MA codes don't allow the Radiant style combined systems, so that isn't an option for me, but I am trying to build as energy efficient a system as possible that will do everything else. Of course right now the GF is out of work, so any home improvements are on definite hold till that changes...

We have a forced hot air system as the existing, so I'm not inclined to try and tie the two together, though I might end up doing that as a transition approach - put in a coil while doing the in floor and use it until all the floors are done....

Gooserider

 

[Fred61]

Last winter was my first season with the in-floor heat and I couldn't be happier. Last fall I had reservations about whether it would heat my living space when it got real cold. There was no reason to worry. The colder it became, the warmer my floors were and the more comfortable I was. Getting out of bed on a cold morning made me wonder if the peasants are shivering.

 

[Fred61]

I must confess that when I first installed the radiant tubing, my intention was to use an oil fired or propane water heater, however as fuel prices increased I decided to go with a wood boiler. At that point I had the floor full of non O2 barrier pex and I wasn't about to pull down insulation, remove reflective foil and remove and replace all the tubing so I went in this direction which is actually the original plan if using a water heater. Situations change when you take 4 years to do a project. No regrets though!