Tempature Drop !

[Trzebs13]

I am wondering if this is normal? When the in-floor in the basement calls for heat, and I have a decent size fire going the water temp drops like a rock if it was at 180 it will drop to 90-120 in a matter of a few seconds. And usually will not get over 140 no matter what size fire is going. The basement in all under one zone. There are 7 runs and about 240' per run. I'm just not really sure that we hooked this up right is just seems like it shouldn't drop so far. I have been burning 7-12" White and Red Oak rounds that were cut about 1 year ago.
I have included a pic of the setup.

Any comments, suggestions?

 

[stee6043]

I think we'll need more info. Are you talking about boiler output temps dropping? Are you sending 180 degree water direct to your in-floor system?

If you're running 90-120 through your boiler you may eventually damage it. You should have a bypass setup with a mixing valve to maintain at least 140 in the boiler. If not, I'd start there. Also let us know if you're not mixing the water before you send it to your in-floor zones. Most people run 140-150 degree water through their in floor zones. 180 seems awfully high.

 

[Trzebs13]

Yes I am talking about the Boiler temps dropping. I do have a mixing valve to lower the water temp that goes into the floor. The white tubes on top is a loop from the boiler. Then it runs down to the mixing valve, then threw the pump and into the floor.

What kind of bypass, another mixing valve? If you could explain or a pic. that would be great.

 

[stee6043]

You should have a bypass loop that connects your supply from the boiler directly to the return going into the boiler. Attached to this is a mixing valve (Danfoss for example) that will maintain 140 degrees going into your boiler at all times. It's certainly not advisable that you continue to operate your boiler with 90-120 degree temps being seen at the boiler for extended periods.

What is your floor loop mixing valve set at? Do you have temp gauges on your supply and return from the floor zones? What size pump do you have? Seems like you're getting a whole bunch of temp drop in your zones. Perhaps your pump is not sized properly or yout tubing could be too small for the load requirements. Many things to consider. But I would start with the bypass loop mentiond above. You need to start protecting the boiler regardless of how well your heat zones are performing at the moment.

 

[mtnmizer]

I can answer in a general way based on my own system. I have radiant in slab
system 9 runs maybe 300 ft each setup as one zone. The slab is insulated with 2" blueboard underneath
and on the sides, which is a notable point. I can fire up the wood boiler to nearly
200 degrees and as you experienced the slab can pull down the boiler temp to under
150 in maybe 15 minutes by pumping into the slab when it's cold. The return line will feel
cold during this time. I have made the slab work by experimenting with it...

The return lines on the pex have a valve on each one. If I shut of 1/3 of the zones
and feed in hot water, I can run this zone until the return line is warm... Also I
have the tempering valve set at 100 which makes a big difference. I then open three
more lines and refire the boiler and heat the other lines then do the last 3. At that
point I could reduce the inflow temp to maybe 90 and run constant if I wanted to.

My system was designed to be run off a condensing lp boiler which is a lot
different than a wood boiler..I talked to a hydronic engineer about this and also
the guys at econoburn and have been advised that my system probabally needs
to be tweeked by splitting the slab into maybe 3 zones and run on a near
constant basis at a low temp from storage..with some slab sensors ect.

There is a time lag between when hot water is fed into the slab and
when the temp rises in the basement. I've only had the wood
boiler for less than a year and am really still learning. I did
my own install under a master plumber and am currently working
on storage. I have been sucessfully using the slab as storage when
the demand is low. The main floor is HW baseboard which needs
higher temps than the slab...I run the boiler until the main demand is
met the manually set the slab zone using the thermostat and by listening
to the boiler fan speed.. Kinda clunky but 45 min of feeding the slab
keeps the house toasty warm for a couple of days...

So long winded enough--your slab is insulated? I hope yes it is.
What is the tempering valve set at? Can you spit the zone into
smaller points. How is your zone pump controlled.. Bottom line there
are lots details to consider...tell us more MM

 

[Trzebs13]

OK, The mixing valve to the infloor is set at 120 when the boiler is at about 180deg but that seems to change when the boiler temp is lower. The mixing valve is a Caleffi mod 221. I do have a temp in the supply but not the return (good idea) I have got a 1/8 hp pump for the floor. There is 2" foam under the and is is run with 1/2 pex 12" on center.

I was looking and see how I could do a bypass loop and the question I have about that is. These mixing valves, are they a proportional style mix that with the dial jus mixes a set amount of fluid or, do they actualy mix per a set tempature?

I could try tweeking the slab like you said, mtnmizer The slab is one zone and is controlled by a thermastat so there is a pump that constintly cerculates through and when the downstairs (slab) calles for heat is turns on the 2nd pump and then feeds the slab.

 

[mtnmizer]

Are the two white pex lines the main loop? and the closley spaced
tees the secondary? How is the boiler plumbed? How many btu's on
the output of the boiler.. can you make a drawing of your system?

I talked with a couple of local hydronic heat guys and read as much as
possible on this web site which is really packed with info. It sounds like
you're really close but need some knowledgeable support to make it
work.. Slab radiant is really nice once it get up to temp. MM

 

[Nofossil]

OK, The mixing valve to the infloor is set at 120 when the boiler is at about 180deg but that seems to change when the boiler temp is lower. The mixing valve is a Caleffi mod 221. I do have a temp in the supply but not the return (good idea) I have got a 1/8 hp pump for the floor. There is 2" foam under the and is is run with 1/2 pex 12" on center.

I was looking and see how I could do a bypass loop and the question I have about that is. These mixing valves, are they a proportional style mix that with the dial jus mixes a set amount of fluid or, do they actualy mix per a set tempature?

I could try tweeking the slab like you said, mtnmizer The slab is one zone and is controlled by a thermastat so there is a pump that constintly cerculates through and when the downstairs (slab) calles for heat is turns on the 2nd pump and then feeds the slab.

They are essentially automotive style thermostats that allow as much bypass as necessary to get the desired outlet temp. There are many other schemes to accomplish the same thing.

 

[Trzebs13]

Are the two white pex lines the main loop? and the closley spaced
tees the secondary? How is the boiler plumbed? How many btu's on
the output of the boiler.. can you make a drawing of your system?

I talked with a couple of local hydronic heat guys and read as much as
possible on this web site which is really packed with info. It sounds like
you're really close but need some knowledgeable support to make it
work.. Slab radiant is really nice once it get up to temp. MM

Yes the White are the main loop and the manifolds are the secondary loop (slab)
The boiler is 130,000 BTU's. Here is a pic of the boiler. The outlet comes from the top and into the expansion tank then goes in the white line to the mail loop. Then enters the pump on the back side and into the bottom back of boiler.

What is the easyest way to make up a drawing?

 

[stee6043]

What size pipe are you running off your boiler? I see red and white pex coming off your boiler supply. If white is supplying your floor zones where does the red go?

You could just draw up a sketch by hand and scan it into a Jpeg to post it. That may be the simplest.

 

[mtnmizer]

A search of this web site will yield a bunch of different drawings,
There some good examples under the stickys.

Did you put in a powerout overheat circuit
or do you have another way of dealing with a power outage with
a full load of wood? MM

 

[Trzebs13]

What size pipe are you running off your boiler? I see red and white pex coming off your boiler supply. If white is supplying your floor zones where does the red go?

You could just draw up a sketch by hand and scan it into a Jpeg to post it. That may be the simplest.

I dont have a scanner. Tonite I will see if I can take a pic of a sketch and see if it turns out.

The white goes into the main loop and the red goes to my detached shop. Which is also in floor heat but is not hooked up yet.

Both the red and the white are 1" pex

 

[Trzebs13]

A search of this web site will yield a bunch of different drawings,
There some good examples under the stickys.

Did you put in a powerout overheat circuit
or do you have another way of dealing with a power outage with
a full load of wood? MM

The Dump zone is the basement floor. One of the thermostats on the top of the boiler is for the air intake open and close and the other is the dump zone which turns on the pump for the basment floor.

 

[in hot water]

A cold, or cool radiant concrete slab will suck a lot of btus. They are considered a high mass distribution system. A cold slab will quickly pull the boiler temperature down. A yard of concrete, wet, weighs about 4000 lbs. A yard covers about 100 square feet 4" thick. When you run the number you will be amazed how many BTUs, and hours (sometimes days) it takes to rev up a flywheel that large. It's a lot like heating a swimming pool.

Be sure the boiler return protection is piped properly to prevent that boiler from seeing return temperatures below @ 140Ft.

hr

 

[Trzebs13]

I'm will be working on the bypass ASAP!
But what are the consequences?

Any where would any one suggest to get the bypass valve?
Thanks

 

[heaterman]

Another thing you can do is to drop the water temp going to the floor. It doesn't need to see 120*. I have many basement slabs that never see over 90*. You can also adjust your flow rate to the floor if you have balancing valves on your manifold. What you are trying to achieve is to balance the "drain" of the floor with the output of the boiler. Slowing the heat transfer rate through either temp or flow will allow your boiler to keep up at its own pace. A concrete slab will drain any boiler as fast as if you simply dumped the water out on the ground and tried to reheat new water as it came into the system. Like Hot Rod said, it is a huge flywheel. Charge it up slow and your boiler will love you.
If you can't throttle your floor delivery back the only option you have to protect your boiler would be a mixing valve or a mixing circulator used for boiler protection.

 

[mtnmizer]

A search of this web site will yield a bunch of different drawings,
There some good examples under the stickys.

Did you put in a powerout overheat circuit
or do you have another way of dealing with a power outage with
a full load of wood? MM

The Dump zone is the basement floor. One of the thermostats on the top of the boiler is for the air intake open and close and the other is the dump zone which turns on the pump for the basment floor.

With no electricity to run the circ pump to the basement you could have an unsafe
situation on your hands. If you search this forum on overheating you will find this discussed
at length. MM

 

[Trzebs13]

I thought I was missing somthing. Thanks everyone for all of your help I really am learning alot from this site.

 

[Gooserider]

As others have said, it sounds to me like the main problem is that you are trying to warm up a cold slab, which takes a LOT of BTU's - you either need throttle down the amount of heat going into the slab loop at any one time, and / or put a return temperature control on the boiler so that the boiler return temp stays above 140* as much as possible. Failure to do this risks flue gas condensation in the boiler and / or stack which can result in major corrosion and failure of the boiler - the pattern of which is pretty obvious, and is NOT covered by any manufacturer warranties....

Having a return temperature control loop is probably the safest approach as it will keep you covered no matter what else is going on in your loads. Next throttle the amount of heat going into the slab at any one time so that you will have enough left for your other loads.

The other concern raised is that of a power fail / pump fail dump zone, which it sounds like you don't really have at present... This a system you should have as protection for the situation where you have just gotten a full load of wood going and the power goes out, a pump quits, or there is some other system failure that causes your normal distribution method to fail, including a boiler over-temp situation for any reason. While a power-failure or boiler overtemp should shut down the fans and reduce the air to the fire, it WILL continue to burn for some time, and produce heat, potentially leading to steam producing temperatures, boiler damage, popping the pressure valve, etc...

Since part of the potential failure scenarios include power failures, the first rule for dump zone design is that it must work without power, and without human intervention. This essentially means it needs to rely on a convection powered gravity or thermosiphon loop, where the hot water rises out of the boiler, cools, and then flows back to the boiler. It needs to be able to get rid about 20% of the boilers rated output. In order for a gravity loop to work, it must be fairly large bore, and not have any major flow restrictions, or dips that would act as thermal flow breaks - and the cooling area needs to be above the boiler. Sometimes one can use existing baseboard loops, possibly with some extra plumbing to bypass pumps and zone controls, but often the easiest way is to run an extra loop of fin-tube around the ceiling of the boiler room. Control is often done by using an "automag" valve, which is a normally open valve that is held closed by the presence of a small amount of electric power. In the event of a power failure or overtemp shutdown, the automag looses power, opens, and the heat flows into the dump zone. (Note that since this is stuff that just sits in the boiler room, it doesn't have to be pretty, many people get their dumpzone fin-tube from the scrap yard, or discounted "scratch & dent" from the plumbing supplier)

Gooserider

 

[Trzebs13]

I am starting to work on getting these problems solved. I am looking specificly for the "bypass" valve any suggestions on what one to get. Unfortunaly I bought this direct and have absoulty NO help from Greenfire or a distrabutor. Which I think there belly up any ways. So in short I really have no one to turn to to help me get this any further than I have got it. One Idea I had was to get a 50 gallon water heater tank and place it in the attic above the boiler room and use one of those valves that were recomended. Does any one think this may not work. I have stopped to 3 different junk yards and called 4 different plumers and am not able to find any finned tubing. And past that I'm like alot of us out there I really don't have a money tree that I can just go shake. But with saying that I realize how important this is so I don't really screw things up.

With the twater tank idea I think you would only need to really cool this for maybe 15 minuites or so before the firebox it self is at a safe level, but I really only am guessing here.

 

[mtnmizer]

Lots of helpfull suggestions to consider.

Your sig lists a new house---call your plumber and see if he would
let you buy from his supplier, they get good quality components
at wholesale prices.

If you do the water tank as a heat sink it wouldn't need be much higher off the floor than the
boiler. That scenario has been mentioned here before.

The valve is what's expensive. Another possibility is a ceiling mount HW space heater or
even cast iron radiators. I saw aa entire HW heating system get scrapped last month
on a major remodel.
Scrounging plumbing shops might be worthwhile.

Also you should be able to add a heat exchanger
and use your boiler with your forced air system/ MM

 

[Gooserider]

I am starting to work on getting these problems solved. I am looking specificly for the "bypass" valve any suggestions on what one to get. Unfortunaly I bought this direct and have absoulty NO help from Greenfire or a distrabutor. Which I think there belly up any ways. So in short I really have no one to turn to to help me get this any further than I have got it. One Idea I had was to get a 50 gallon water heater tank and place it in the attic above the boiler room and use one of those valves that were recomended. Does any one think this may not work. I have stopped to 3 different junk yards and called 4 different plumers and am not able to find any finned tubing. And past that I'm like alot of us out there I really don't have a money tree that I can just go shake. But with saying that I realize how important this is so I don't really screw things up.

With the twater tank idea I think you would only need to really cool this for maybe 15 minuites or so before the firebox it self is at a safe level, but I really only am guessing here.

I think the water tank in the attic might work, especially if it is NOT insulated (remember the idea is to get rid of as much heat as possible) but you do need to keep it protected from freezing. Another variant I've heard of is to use a good sized old fashioned cast iron radiator...

You might not be asking the scrapyards or plumbers for the right stuff - if they dont have fin-tube, ask for old baseboard... Look for places that get old plumbing, or building deconstruction stuff... Also rather than asking plumbers, ask the plumbing SUPPLY houses where the plumbers get their stuff - they are more likely to have shipping damaged material that they are having trouble getting rid of than the individual plumbers.

On the boiler protection, there seem to be a great many different options, each with it's own advantages and disadvantages, ranging from thermostatic mixing valves to temperature controlled pumps, to the Termovar valves. Do a search on "boiler protection" and I'm sure you'll find plenty of discussion on the different options.

Gooserider

 

[Trzebs13]

Lots of helpfull suggestions to consider.

Your sig lists a new house---call your plumber and see if he would
let you buy from his supplier, they get good quality components
at wholesale prices.

If you do the water tank as a heat sink it wouldn't need be much higher off the floor than the
boiler. That scenario has been mentioned here before.

The valve is what's expensive. Another possibility is a ceiling mount HW space heater or
even cast iron radiators. I saw aa entire HW heating system get scrapped last month
on a major remodel.
Scrounging plumbing shops might be worthwhile.

Also you should be able to add a heat exchanger
and use your boiler with your forced air system/ MM

Yep I do have a heat exchanger hooked in to my forced air

 

[Trzebs13]

Well the plumer called and I have a 40 gallon hot water heater on the way. So I plan on putting this up in the attic as my "safty cooler" in case of a power outage. the one thing I'm wondering is what would be the minium size piping that I should run to get a good gravity feed? To get the boiler cooled down. I plan on stripping the heater down to the bare tank. And the other thing is would it make a diffrence if I layed it down or not and of so where should the in and out go? What I'm thinking is that the inlet should be on top and the outlet be on the bottom. Does this sound right?

 

[mtnmizer]

Well the plumer called and I have a 40 gallon hot water heater on the way. So I plan on putting this up in the attic as my "safty cooler" in case of a power outage. the one thing I'm wondering is what would be the minium size piping that I should run to get a good gravity feed? To get the boiler cooled down. I plan on stripping the heater down to the bare tank. And the other thing is would it make a diffrence if I layed it down or not and of so where should the in and out go? What I'm thinking is that the inlet should be on top and the outlet be on the bottom. Does this sound right?

As an unqualified amateur my answer to your question is that
I'd locate a tank vertically as close to the boiler as possible, elevate it somewhat maybe 2ft
plumb it with black steel pipe, 1.25". not pex using as few elbows as possible.. hot out from boiler to hot on
top of tank return from bottom. Control valve on in line iso valves on both lines.
I wouldn't be very comfortable putting a water tank into an attic.

And since this is experimental I'd bring up the boiler to max temp and see how it works. MM