Primary Loop pump

frank_31

I am currently having a house built and am running into some serious heating issues. I have a Dunkirk propane boiler hooked up to heat my 6 zones(4 hot water baseboard, 1 basement radiant heat, and 1 domestic hot water) in my house and an outside wood boiler connected(heat exchanger) to the return line going into the propane boiler. There is no primary loop circulator pump installed and when the house starts to call for heat after a period of inactivity the propane boiler kicks on and fires for about 5-7 minutes to get the idle water up to temp. My question is do I need to have a primary loop pump to keep the propane from firing? Also I have a problem with the living room(large cathederal ceiling w/ windows)/kitchen zone calling for heat and the system running for about a week and a half just trying to get it up to 68 degrees, it would not heat up from 64 deg. The outside temps ranged from 20 to -15 degrees. The house finally came up to 68 after the sun came out and the outside temp rose to about freezing. Then dropped back down to 64 degrees after sunset and the temp dropped back to 20 deg. Any help would be greatly appreciated. I am a baffled new home owner and need some assistance. I have digital pics of the set up in the basement if anyone would like to see them.

Weezbo

I would like to see the jpegs of the boiler and associated

piping....it helps bring things to focus...

frank_31

pics

I'll try to get the pics posted later today.

Mad Dog

Your system may need that

but boiler pioctures are a must. That room may just be under-radiated too. Mad Dog

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frank_31

pics

Thanks for the replies so far. Here are some pics to give you guys some idea of what the heating setup looks like. If we need more just let me know and I'll try to get them. Thanks

bob_44

Primary Loop

Frank, From what I can see in the fotos your system is piped two pipe parallel direct return. There is no primary loop. This may be a mater of semantics. In my lexicon you have to be piped primary/secondary to have a primary loop. Are you refering to the loop from the heat-x to the wood boiler as the primary? bob

Jim Burke comfort zone

Hard to tell from pic but it looks like the mixing valve for radiant is on the the outlet side of your pump .
Also what is going to circulate water thru your xchanger.




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hr

Need to know, also

if those zone pumps have enough fizz to run the plate HX, in addition to the zones connected to them.

The HX design info will give you a pressure drop #er at various flow rates.

I think a true primary loop may have served you better with the various heat source and loads you have.

I assume you are pumping the "A" side of the HX from the pump at the outdoor wood boiler? This pump, also has to be sized to proberly flow the HX for the BTUs you are trying to move and exchange.

With us so far?

With this drawing all the various loads and heat "adders" can come and go as they please without upsetting one another hydrauliclly speaking.

The PONPC is within the primary loop, in this case, and as such all loads, and inputs pump away from that.

hot rod

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hr

A little unusual

all your zone circs flow through the HX, is this correct? So when one zone calls you need enough circ to flow the zone and the plate HX. Everything changes when all circs are running.

Does the wood boiler have a circ that flows the "A" side of the HX. Is it sized correctly?

A true primary loop may have served your needs better. It allows those various loads and boilers to come and go without upsetting the hydraulics. High head and low head circs mix better in P/S.

In this drawing the PONPC is within the primary loop. As such all loads and sources pump away from this for a air and troublefree system.

You will need to crunch some numbers to see if and how well you system will work.

hot rod

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frank_32

wow

Hey thanks for he responses. Unfortunately I do not quite know how to answer some of the questions. I am as clueless as it gets when it comes to this heating system. I know that the water sits idle in the propane boiler until one of the zones calls for heat. then the propane boiler kicks on and circulates the water which when the water hits the return line where the heat exchanger is plumbed in, the water is heated to temp(usually 170-180 deg) quickly so the propane kicks off and the zone calling for heat continues to circulate the water. The outside wood boiler circulates constantly to the heat exchanger. The wood boiler is actually considered the backup system even though i use it as the primary source for heating. I believe that the baseboard in my living room/kitchen area is not adequate enough to heat the area. so there are actually two separate areas of concern here. The propane boiler kicking on due to the water sitting idle and not staying at a constant temp. And the inadequate amount of baseboard in the kitchen/living room area. I was just curious about putting a primary loop pump on the loop coming out of the propane boiler but with the loop being interrupted by the mixer going into the floor heat. I guess that I am just baffled by this and better get the experts involved. thanks for everyones input.

james k

wood boiler

> Hey thanks for he responses. Unfortunately I do

> not quite know how to answer some of the

> questions. I am as clueless as it gets when it

> comes to this heating system. I know that the

> water sits idle in the propane boiler until one

> of the zones calls for heat. then the propane

> boiler kicks on and circulates the water which

> when the water hits the return line where the

> heat exchanger is plumbed in, the water is heated

> to temp(usually 170-180 deg) quickly so the

> propane kicks off and the zone calling for heat

> continues to circulate the water. The outside

> wood boiler circulates constantly to the heat

> exchanger. The wood boiler is actually

> considered the backup system even though i use it

> as the primary source for heating. I believe

> that the baseboard in my living room/kitchen area

> is not adequate enough to heat the area. so

> there are actually two separate areas of concern

> here. The propane boiler kicking on due to the

> water sitting idle and not staying at a constant

> temp. And the inadequate amount of baseboard in

> the kitchen/living room area. I was just curious

> about putting a primary loop pump on the loop

> coming out of the propane boiler but with the

> loop being interrupted by the mixer going into

> the floor heat. I guess that I am just baffled by

> this and better get the experts involved. thanks

> for everyones input.

james k

wood boiler

Frank,
What temp. is your outside boiler? Your outside boiler
should be 20* higher or more than the inside one or you'll
just be heating the outside boiler instead of vise-versa.
I agree with the diagram drawn by Hot Rod (I believe).
You need primary/secondary piping. I've seen the info from
the outside wood boiler guys, their idea of radiant mixing
is a couple of valves. The ones that I've done have been with primary/secondary piping. You get very little benefit
from the outside boiler with it piped into the return line.How would you even use it as the principal heat source,
turn off the inside boiler, turn down the temp. setting?

frank_31

the propane heating system was actually installed by my contractors and the outdoor wood boiler guys came and installed their end of the system. the wood boiler guys are the guys pushing for the primary/secondary system. the primary pump would keep the circulating water at a constant heat where as the current system just lets the water sit idle until a zone calls for heat. the inside high limit is turned down to attempt to keep the propane from kicking on everytime the system calls for heat. the thermometer just coming out of the propane boiler shows about 170 deg when the water is flowing constant and zones are calling for heat. the plumber said the thermometer is about 10 deg. off so i am losing very little from the wood boiler to the inside since the wood boiler is set at 180 deg. i hate hearing the propane kick on every time the system calls for heat since the wood boiler is supplying more than enough heat to the exchanger and system. so far since the beginning of december i have burned over 40% of a 250 gallon tank of propane, over 4 full chords of firewood, and 1 ton of coal, trying to heat my 2000 sq ft house that I'm not even living in yet. thats all with the wood boiler running 24/7. thanks for your time on this guys I am really lost.

hr

If in fact the

wood boiler pumps run continously, every time you fire the LP you are sending heat from the LP boiler to the wood burner. So if the wood boiler is not fired, or warmer than the LP, you actually have a cooling tower in the yard! This would seem to consume more, not less LP.

I'm not sure you can accomplish what you intend with that piping arrangment. I've seen some pretty unusual boiler tie in from the wood burner manufactures drawings

hot rod



hot rod

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Glenn_3

You could..

Put a simple delay on timer between your taco controller and your propane boiler that would keep it off until your wood stove had enough time to bring loop temp up.

But I agree a P/S setup would be the way to go in the long run.

S Davis

Backflow Preventer

I would look at getting a backflow preventer installed on that system unless it has one that can not be seen in the pictures.

S Davis

Apex Radiant Heating

frank_31

thanks for the insight everyone. i am pushing for the primary/secondary loop but the contractor seems to think that there is currently no problem. we'll have to see how it plays out here soon. i wish it would drop back down into the 0 degree range so they could see how the system is actually inadequate in its current configuration.

hr

Add some numbers Frank

actually 40% of 250 gallons of LP = 100 gallons. That's not bad for 2 months plus. It does DHW and?? cooking, clothes dryer?

However a ton of coal is about 22,000,000 BTU, four cords of mixed hardwood about 56,000,000. So you burned 78 million btus worth of solid fuel? Call the outdoor stove 40% efficient. So 31000000 BTU should have been useable from the wood and coal. If my math is correct Add to that the LP consumed from the start of heating season at 92,000 BTU per gallon at 85% efficiency.

I don't know your climate, and when you started the heating season but this sounds like a lot of combined fuel consumption for the size home you have?

In all fairness the boiler guys work in not bad. Your problem (or their problem)is the way the outdoor wood burner is tied in and controlled.

You don't ever want the LP boiler heating the outdoor burner, period. They need to be seperated mechanically (hydraulicly) and with the operating controls.

A simple differental control would make them get along control wise. However you would need some wiring between the boiler and the wood burner to make this happen. Adjust it so the LP only fires when the outdoor furnace drops below say 140°. AND stop the flow to the outdoor unit when the lp fires. Stopping the outdoor pump may help, however might thermosiphon without check valves or P/S piping.

As for the LP boiler short cycles. With the number of zones you have it is possible, at times, that only 1 zone pump could be running. This will cause the boiler to short cycle somewhat, if the boiler cannot modulate it's output. Not a lot you can do about that. Widen the boilers aquastat delta T may help some.

The limited output at the baseboard could have to do with the pressure drop through that plate HX as all boiler flow goes through it all the time a zone is calling. The spec sheet on that HX would help determine that issue.

Sounds like you have opposing forces working here the boiler guy and the outdoor furnace guy.

You NEED them both on the same page to make this happen. It's your fuel dollars they are playing with

hot rod

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frank_31

Hotrod,

I think you nailed it here. There are three people here on the same page.... you, me, and the outdoor wood boiler guy. Unfortunately the propane boiler installer and his employer, my contractor, do not see it that way. I have a coworker that has the same size house and similar inside boiler and wood boiler. His system works on the primary/secondary concept and works flawlessly. He got about 13 hours minimum burn time out of his wood boiler on the worst days we had sofar this winter. And burned zero propane in the process. I cannot get that through to my contractor. I try to explain to them that I am going thru fuel like crazy whether its lp, wood, or coal. I have been running the lp since the begining of december and had the wood boiler installed on 12/9/04. I did not start burning coal in it until 12/20. And back in jan. we went thru about a week of 20 degrees and below, all the way to -15 deg. including during the days. So the winter has been harsh for a few days but overall we have had a real mild winter here in upstate pa. we have been running temps in the mid 30's on a regular basis which is not normal for this time of year, with alot of sun. My house has been staying up to temp without a problem durin this nice weather but it still comes back to how it dropped to 64 and stayed there during that cold spell. I think that its crazy that a brand new well insulated home is unable to stay up to 68 deg and runs for a week and a half solid to get off of 64 deg. Maybe I am asking for too much from my current system, but I cant see how with all the fuel that I have burnt so far. Thanks for the insight. Eventhough I don't understand everything that everyone has discussed, i am learning and appreciate it.

frank_31

I forgot to mention that I am currently not living in the new house yet, so the domestic hot water is not being heated. And there isn't the opening and closing of doors letting in cold air. Originally the high limit was set at 140deg to keep the propane from kicking on but has since been turned up to an unknown setting.