Hydronic heating via Radiator's - Using a Wood heater with a wetback/water jacket

[St Marys]

G'day,

I'm new here & have had a bit of a look around, so please excuse me if this post should be in another section.
I live in Australia & while I have been heating my house with wood successfully for 15 years, we are about to extend our house by about 700Sq Ft & due to the lay out it seems we need to install a secondary heat source. The simple solution would be a second wood heater, however I have been exploring Hydronic heating as an option.
The house is on stumps with a timber floor, it was built in the 1860's which is quite early out here. I have access to a number of cast iron radiators which it would seem area good option to heat the rooms. Our current fire place does not have a water jacket, however I am prepared to purchase one.

I'm sure that this has been covered before, I just haven't been able to find it, probably as i am not using the right terms.

The main questions at this point I have are of sizing of the heater it's self/fire box, the size the water jacket needs to be, the size of panel that a room needs & the flow rate of water through the system. At this stage I am not looking to use it for hot water in the house, just as a means of moving heat around the house. We currently have solar hot water with a propane booster. I like the idea of connecting the house hot water to the system but don't want to complicate things so soon.

I hope my rambling's make sense, I also understand that there are many questions I am not aware I need the answers for yet.

Regards

 

[salecker]

Hi
It's nice to have someone from another part of the world join up for information.
The information you are looking for might be hard to find here as most installations have a factory designed water heater/boiler.
Myself i do have cast iron rads in my house and love them.At -40C it's like having a wood stove in each room.
I have a gasification boiler and 4500 liters of hot water storage that runs my house during the day while i am at work.
If you search and read you will find some threads on homemade boilers,water heaters, and even sod covered pizza ovens that people say they use to heat their homes.
Spend you extra time reading on here.I did a i feel like this site saved me from building a system that would not have performed well enough to get me through a Yukon winter in comfort.
Weeks of -40 C in the winter are no issue for my house, now the wood pile on the otherhand does not like -40 C.It evaporates in the cold

 

[St Marys]

Hi
It's nice to have someone from another part of the world join up for information.
The information you are looking for might be hard to find here as most installations have a factory designed water heater/boiler.
Myself i do have cast iron rads in my house and love them.At -40C it's like having a wood stove in each room.
I have a gasification boiler and 4500 liters of hot water storage that runs my house during the day while i am at work.
If you search and read you will find some threads on homemade boilers,water heaters, and even sod covered pizza ovens that people say they use to heat their homes.
Spend you extra time reading on here.I did a i feel like this site saved me from building a system that would not have performed well enough to get me through a Yukon winter in comfort.
Weeks of -40 C in the winter are no issue for my house, now the wood pile on the otherhand does not like -40 C.It evaporates in the cold

Thanks for the welcome,

Our temps are not anything like yours, I could imagine a wood heap would evaporate very quickly at -40 C! A very cold over night would be -4 C. however we use our wood heater probably 5 months a year,
I have a the option of having a wood heater built, but as hydronic heating is not that common, particularly using radiators finding information is difficult, it almost seems like it is secret society!
I just want to make sure I am in the ball park with my sizing, I don't want to buy too many things twice!

 

[salecker]

When i built my system i couldn't find much on old cast iron radiators output.
I restored all the ones i used,i had planned on using more than i did.Most of the time the old way of thinking was a heat register under the windows.On my main floor i started with 2 4 ft CI rads next to each other that are next to the stairway going into the basement.The one bedroom and bath have thier own controlled by TRV's.I have quad pane windows in my house and the first winter showed there was zero reason for heat by the windows as they perform remarkably. At -40C you can sit on the couch under the window and there is no cold feeling down your back from the window. I still have a couple rads i haven't hooked up on the main floor as the access is limited for the one under the floor,and the main area of the house stayes warm in the cold.

 

[St Marys]

When i built my system i couldn't find much on old cast iron radiators output.
I restored all the ones i used,i had planned on using more than i did.Most of the time the old way of thinking was a heat register under the windows.On my main floor i started with 2 4 ft CI rads next to each other that are next to the stairway going into the basement.The one bedroom and bath have thier own controlled by TRV's.I have quad pane windows in my house and the first winter showed there was zero reason for heat by the windows as they perform remarkably. At -40C you can sit on the couch under the window and there is no cold feeling down your back from the window. I still have a couple rads i haven't hooked up on the main floor as the access is limited for the one under the floor,and the main area of the house stayes warm in the cold.

Thanks so much, that is good info. Any chance you know how much volume your system has & what the output volume of the pump is?

 

[salecker]

I have 4500 liters of insulated storage
I have a bigger pump that runs continuosly suplying the house,i will have to look at the number from it.

 

[coaly]

2 ways, first decide if it needs to be a sealed system to pump longer distance, or “open system” if the stove is near the addition to circulate with natural rising of heating in the coil or water back.

A sealed system requires oxygen barrier tubing, an expansion tank, pressure relief valve, and circulator pump. It builds up pressure when heated and has a auto fill valve with pressure regulator, filling the system with no more than 15 psi cold. It will use a 30# pressure relief valve.

A gravity system, or open tank type is much simpler, should be close to the addition, and works well as long as the details of correct engineering are followed. The coil, or water back needs a hot outlet on top, and cool return on bottom. Oversize pipe from stove to radiation, this decreases friction allowing free movement, and can be throttled with a valve to reduce circulation as needed. Water rises where heated in coil, moves to nearby radiator through an upper line, where it cools as it drops moving through radiator to return to coil to be reheated. The highest point needs a water tank, open to the atmosphere to monitor water level to keep full. It will get hot enough to vaporize into the air, humidifying the interior heated space as well.

“Kitchen Boiler Connections” is a favorite of mine from 1902 with detailed illustrations.

 

[salecker]

Just a point of clarification...
A closed system does not have to have an auto refill valve.I have never had one in my system.
I have not added any water since i got the proper amount of expansion tanks to handle the expansion of 4500 liters+ of water.
It is a luxury item, that can give you head aches if it starts acting erratic.
If you add a low water shutdown that would give you peace of mind.I don't have one on my system either.
Now mind you , my system is made up of tested components, plus i tested the complete system to 80 PSI before i ever fired it up.This was a test done by having the complete system filled with water then pressurizing with air pressure.
You have to fill the system with water to test safely, if you use just air you have a potential lethal bombs of all components if one fails.
My Cast Iron Rads received the same testing as they were reclaimed from mother nature.I found them in the bush with willows growing through them.My estimation were they had been there for 40 years.A few more and they would have been never been seen.

 

[St Marys]

2 ways, first decide if it needs to be a sealed system to pump longer distance, or “open system” if the stove is near the addition to circulate with natural rising of heating in the coil or water back.

A sealed system requires oxygen barrier tubing, an expansion tank, pressure relief valve, and circulator pump. It builds up pressure when heated and has a auto fill valve with pressure regulator, filling the system with no more than 15 psi cold. It will use a 30# pressure relief valve.

A gravity system, or open tank type is much simpler, should be close to the addition, and works well as long as the details of correct engineering are followed. The coil, or water back needs a hot outlet on top, and cool return on bottom. Oversize pipe from stove to radiation, this decreases friction allowing free movement, and can be throttled with a valve to reduce circulation as needed. Water rises where heated in coil, moves to nearby radiator through an upper line, where it cools as it drops moving through radiator to return to coil to be reheated. The highest point needs a water tank, open to the atmosphere to monitor water level to keep full. It will get hot enough to vaporize into the air, humidifying the interior heated space as well.

“Kitchen Boiler Connections” is a favorite of mine from 1902 with detailed illustrations.

Just a point of clarification...
A closed system does not have to have an auto refill valve.I have never had one in my system.
I have not added any water since i got the proper amount of expansion tanks to handle the expansion of 4500 liters+ of water.
It is a luxury item, that can give you head aches if it starts acting erratic.
If you add a low water shutdown that would give you peace of mind.I don't have one on my system either.
Now mind you , my system is made up of tested components, plus i tested the complete system to 80 PSI before i ever fired it up.This was a test done by having the complete system filled with water then pressurizing with air pressure.
You have to fill the system with water to test safely, if you use just air you have a potential lethal bombs of all components if one fails.
My Cast Iron Rads received the same testing as they were reclaimed from mother nature.I found them in the bush with willows growing through them.My estimation were they had been there for 40 years.A few more and they would have been never been seen.

Thankyou,

A couple of points of interest, here in Australia it is unusual to have a basement, I am not sure why but is the case.

From what I have read is is common to have a boiler setup in the basement & in the case of an 'Open' system the water would thermo syphon - If set up correctly - would circulate around the system without any further input - ie pumps etc.

At this stage the longest distance the water will need to travel is 50 feet, to the furthest radiator. I think due to simplicity the open system is the direction that i will head, potentially without a storage cylinder & due to the wood heater/boiler being on the same floor as the radiators there will be very little ability to 'thermo-syphon' so I will need a water pump to push the water around.

At this point a few of the questions I have are,
- how much water should the water jacket hold?
- what sort of flow do I need.
- How do i work out the heating 'capacity' of a radiator - as I am hoping to use old radiators without specifications I don't have a way of knowing what their capacity is, except via maths.

Now I understand that there are so many variables with all of this, 'what is the volume of the system when it is full of water', 'how much heat output does the fire place have?', 'how efficient is the house & how much input does it need to keep warm?' 'how many radiators will be in the system?' ,

I have found a range of pumps which will work, these have 3 speed settings & can cope with 100deg Celsius water (boiling) the plan would be to put this in the return line, so the water is much cooler & be less harsh on the pump.

I have attached a copy of a schematic as supplied by a wood heater manufacturer as a reference.

Regards

 

[coaly]

Yes, 50 feet requires a pump. Insulating the hot line gets hotter water to the radiator.

That attachment is a much more complex design than I was referring to. I was referring to a simple loop to move heat to another area on the same level.

Radiation size depends on water temperature which has too many variables. Normally baseboard sections below each window is done here. When a series of radiators are used, the first will be hotter as the water circulates to the next. If you want more even heat, a bypass pipe goes around each radiator. A valve installed on this line determines how much goes through each radiator, or bypasses it.

One main factor is the hotter the water, the faster the heat is transferred to air. This is why boilers should be closer to 200*f than 180* or lower. Once you know the water temperature at radiator, you can determine how much radiation is required. A flow valve with bypass at each radiator makes it totally adjustable.

Water volume changes the duration of time between hot cycles burning wood. The smaller the tank the faster the response at radiators. Larger tanks, and insulating them gives storage of heat you may or may not need. For direct circulation, only a small cistern is needed of a few gallons. It is more of an expansion area, filling, and humidifying. My 25 gallon tank is also used for hot water, vented for humidification. It is nice to have a adjustable vent opening to control humidity. Mine uses maybe a gallon a week heating 1800 sq.ft.

 

[St Marys]

Yes, 50 feet requires a pump. Insulating the hot line gets hotter water to the radiator.

That attachment is a much more complex design than I was referring to. I was referring to a simple loop to move heat to another area on the same level.

Radiation size depends on water temperature which has too many variables. Normally baseboard sections below each window is done here. When a series of radiators are used, the first will be hotter as the water circulates to the next. If you want more even heat, a bypass pipe goes around each radiator. A valve installed on this line determines how much goes through each radiator, or bypasses it.

My plan was to have a by-pass valve at each Radiator so that it can be 'tuned' to better disperse the heat according to our needs,

One main factor is the hotter the water, the faster the heat is transferred to air. This is why boilers should be closer to 200*f than 180* or lower. Once you know the water temperature at radiator, you can determine how much radiation is required. A flow valve with bypass at each radiator makes it totally adjustable.

This will be difficult to determine in the planning stage, due to the number of variables, I am hoping that I can get this into the right ball park so that the flow rate at the pump will help balance the system. Determining the amount of flow required might be a little difficult to work out. As well as the size of the wood heater - capacity of the fire box - & volume of the 'boiler' or 'water jacket'

Water volume changes the duration of time between hot cycles burning wood. The smaller the tank the faster the response at radiators. Larger tanks, and insulating them gives storage of heat you may or may not need. For direct circulation, only a small cistern is needed of a few gallons. It is more of an expansion area, filling, and humidifying. My 25 gallon tank is also used for hot water, vented for humidification. It is nice to have a adjustable vent opening to control humidity. Mine uses maybe a gallon a week heating 1800 sq.ft.

Direct circulation is a term I havn't seen or used but it well be helpful to describe what we are hoping to do.
The part about 'vented for humidification' what do you mean by this - what is the function? Also your comment about having an adjustable vent opening to control humidity? A friend who has a set up similar to the one being discussed has a 'tap' or 'faucet' (I think that term is right?) which is a bleed for pressure, he said it was just cracked - turned on ever so slightly. I had wondered if a pressure relief valve from a hot water service might be neccessary as a back up should the water pump die/power outage etc

Our place will be nearly bang on 1800sq.ft when done, as a reference.

@coaly thanks for your input.

 

[salecker]

Just get some TRV`s for the rads
You set them for the temp you are comfortable at and they do the rest.
No electricity or wires. No forgetting to turn them on.

 

[coaly]

My plan was to have a by-pass valve at each Radiator so that it can be 'tuned' to better disperse the heat according to our needs,

This will be difficult to determine in the planning stage, due to the number of variables, I am hoping that I can get this into the right ball park so that the flow rate at the pump will help balance the system. Determining the amount of flow required might be a little difficult to work out. As well as the size of the wood heater - capacity of the fire box - & volume of the 'boiler' or 'water jacket'

Direct circulation is a term I havn't seen or used but it well be helpful to describe what we are hoping to do.
The part about 'vented for humidification' what do you mean by this - what is the function? Also your comment about having an adjustable vent opening to control humidity? A friend who has a set up similar to the one being discussed has a 'tap' or 'faucet' (I think that term is right?) which is a bleed for pressure, he said it was just cracked - turned on ever so slightly. I had wondered if a pressure relief valve from a hot water service might be neccessary as a back up should the water pump die/power outage etc

Our place will be nearly bang on 1800sq.ft when done, as a reference.

@coaly thanks for your input.

Our winter air here is very dry. Water kettles are placed on stoves, and places with hard water, meaning minerals are best using stainless steel pans. An open system having a lid with adjustable vent controls how much evaporates from the tank into the air, or closing it condenses on the lid dripping back into the tank. You may not need to add moisture to the air there.

A pressure relief valve is needed in any sealed system that builds pressure as water is heated.

 

[St Marys]

Just get some TRV`s for the rads
You set them for the temp you are comfortable at and they do the rest.
No electricity or wires. No forgetting to turn them on.

Thanks, there are lots of terms which are new to me, it makes it easier to know what to look for, have found a type & a local supplier, thankyou

Our winter air here is very dry. Water kettles are placed on stoves, and places with hard water, meaning minerals are best using stainless steel pans. An open system having a lid with adjustable vent controls how much evaporates from the tank into the air, or closing it condenses on the lid dripping back into the tank. You may not need to add moisture to the air there.

A pressure relief valve is needed in any sealed system that builds pressure as water is heated.

I get it now, we certainly don't need humidifiers during the winters here,

Re pressure relief valves, what kind of pressure is considered too much? 1.5 - 2 bar?

 

[coaly]

Thanks, there are lots of terms which are new to me, it makes it easier to know what to look for, have found a type & a local supplier, thankyou


I get it now, we certainly don't need humidifiers during the winters here,

Re pressure relief valves, what kind of pressure is considered too much? 1.5 - 2 bar?

Low pressure hydronic systems here are 30 psi, or 2.068 bar. The fill valve has a 12 to 15 lb. regulator. Filling over 15 psi cold can allow the expansion when heated to open relief valve.

 

[St Marys]

Well, I bought one of these today, secondhand, it will be big enough for our house well & truely, it came with a pump that is the same as the one in the house it came out of. looks to be in good nick, it will be interesting to see how it all comes together.

Dynamic 3500 - Hydronic Wood Boilers Australia | WISELIVING

A versatile, dedicated hydronic heating boiler with cleverly designed waterways and smoke paths to gain the maximum heat from its compact size.

www.wiseliving.com.au

 

[salecker]

Good Call
you have a safe starting point for your heating system now.
You can always experiment on heating for a shop.

 

[St Marys]

Good Call
you have a safe starting point for your heating system now.
You can always experiment on heating for a shop.

Thanks, still a few things to work out, but we are nearly there,

Question, how much difference does colour & paint type change a radiators ability to release heat into a room?

Also is it neccessary to have a smaller cold return pipe or can it be the same size as the supply/hot side?

 

[salecker]

Flat black is the best to shed heat...
At least it is if you have a racing engine.I learned that from Smoky Yurnick who was one of the best engine builders in the stock car racing circuit in the states for years.
All my rads are flat black,except the one in my daughters bathroom,which is white.

 

[mark cline]

Have you looked into radiant floor heating? Your floor is the radiator so no bulky radiators taking up space . With a mixing valve, your water temperature could be lower , like 17-18C. I think you might be trying to heat your water up say 82c , which in turn may overheat the part of the house where your boiler is at . Just looking at it from a different angle.

 

[RomanPadilla]

It's fantastic that you're considering Hydronic heating for your home expansion in Australia. Using cast iron radiators can be a great choice. If you're looking for expert advice and insights on sizing, water jackets, and other aspects of your system, you might want to explore Radiator Village. They're known for their expertise in radiators and might have valuable recommendations tailored to your specific project.

 

[RomanPadilla]

It's fantastic that you're considering Hydronic heating for your home expansion in Australia. Using cast iron radiators can be a great choice. If you're looking for expert advice and insights on sizing, water jackets, and other aspects of your system, you might want to explore Radiator Village. They're known for their expertise in radiators and might have valuable recommendations tailored to your specific project.

P.S Your questions are valid, and you're in the right place to gather information and make informed decisions.

 

[all night moe]

Hoping the OP is still around to share some updates. I'm getting much closer to building a hydronic system myself.

1st floor: temporary WTA heat exchanger in existing ductwork. Future radiant floor or CI rads.
2nd floor: CI rads with insulated supply loop in attic.
Heating 4500sq ft.

 

[St Marys]

Hoping the OP is still around to share some updates. I'm getting much closer to building a hydronic system myself.

1st floor: temporary WTA heat exchanger in existing ductwork. Future radiant floor or CI rads.
2nd floor: CI rads with insulated supply loop in attic.
Heating 4500sq ft.

Yep I'm still here, I ended getting some old cast iron radiators which I have had blasted & about to paint. In about 3 weeks the system will be functioning I can show photos & describe the system a little better. We found someone local who was happy to do the installation. I will keep you posted