HELP system draining

[VTVt]

HELLO,

I have just installed a MAXIM250 outdoor pellet boiler.... it is located at or just above the same level on the ground outside as my indoor oil burner is inside.... so it is not much higher than the indoor system. My building is 3 stories, and the first story where the indoors system is located is ground level... there is no "below ground basement", the first floor is the basement... slab/walkout/ground level.

We hooked it directly to the oil burner, and it seems my indoor system lost water, out the outdoor vent.... my indoor system read zero pressure in the boiler....

it heated great as far as heating goes, but with the loss of water in my system inside, we ended up with some cold rooms, in other words not enough water going around....

today we turned off the outdoor unit, fired up the indoor unit, and refilled all my pipes and bled all the rooms.... hours of work.

The stove dealer said try opening the return valve first, then open the feed (from the outdoor unit) ..... with the hopes it would equalize and not dump out all my indoor pipes out the vent. WELL, I opened the return slowly just partway.... and outside the water was flowing out the vent.... we tried opening the feed line a bit to let it back in the building, but it did not seem to be working... after watching my indoor system go from 22 pounds to 18 in a few seconds, we closed off the outdoor valves. I did not want to empty my system again especially since it was now night and we needed heat and I was not going to deal with bleeding all rooms again all night.

SO will I be able to do this or is there a RULE OF THUMB regarding outside boiler height/grade/ as related to indoor boiler height/location..... such as "to keep water in the indoor system for two floor levels your outdoor boiler should be so many feet above the indoor unit" etc?

I need to know if it is worth relocating my outdoor unit or just going with a heat exchanger....

DOES ANYONE have experience with this? It seems I will have better heat temps with the direct feed if possible.... but if I move my outdoor unit to higher ground and it still does not work I will get a bit GRUMPY ....... does anyone use one with a building with several floors?
Does anyone know the cost of a heat exchanger for my indoor unit?

SO tonite I am running oil.... sigh sigh sigh

Any feedback appreciated! Thanks! - frustrated in vermont

 

[Tony H]

I don't have an answer but I can tell you that if you are able to post a diagram of your system layout showing all the components and connections it would be much easier to get some help. Moving the system should not be needed, with the proper design and connections the hot water piping will work across different elevation just fine.

 

[Justburnit]

I would check or replace the safety valve on your outdoor unit.

 

[jebatty]

I believe your OWB is an open, non-pressurized, system. Therefore, unless you use a heat exchanger (typically flat plate) to isolate the OWB from and transfer heat to, the pressurized oil burner system, the oil burner system will drain into the OWB until pressures are equal, and if the OWB elevation is below the highest point in the house, all points in the house above this elevation will drain and be without water.

If you are using a heat exchanger, and you still are losing pressure, then I believe your heat exchanger has been improperly installed.

See: http://www.maximheat.com/systemexistingboilertech

 

[VTVt]

OK me again.... I thought so, that my Outside PELLET Boiler, NON-Pressurized would not work since it is at ground level and I have 3 levels.... I am a bit TEED OFF because if this was told to me from the start I could have my parts and would have installed the plate from the get go.... I had told them my OPB would be only a foot or so above the level of my InsideOilB and that I had 3 levels and was told it would be OK. Immediately my IOB drained to Zero pounds of water so then had to shutdown OPB and refill IOB and 3 floors of pipes and bleed etc etc HOURS of work over 2 days...

Also I have read many many websites, posts like these and info in general regarding OB's and have not ever read anything discussing this issue.... even the info on the boiler site does not discuss this issue.... would have been nice to know.... I was wondering about this issue from day one, before I had my boiler and was told by several folks in the biz OH DO NOT WORRY IT HOLDS IT EQUALS OUT AND WILL NOT DRAIN YOUR SYSTEM.... well, apparently not.

Maybe some folks want to run their indoor systems on HALF full of water, (which mine would hold probably IF I only had 2 stories and not 3) but I would not..... the pipes would gurgle and be noisy and with all that air/emptiness running around in half the pipes you risk freezing.

You would think this would be an issue that was listed with all outside unpressurized units... that they would discuss the placement in case you had options/higher ground. It was not discussed anywhere that I could find.

Another thought was to restrict the return so it wont just pump out all over, may try that before giving up...

OK thanks all... sadly burning oil today.

 

[jebatty]

Easy to understand the frustration. Without casting too much blame, many dealers always emphasize cost factors, and one way to low ball is to conveniently omit needed parts and plumbing for the system to operate.

I don't think restricting your return will help; it will slow down just a bit the draining, but result will be the same.

Does your OPB have a weighted vent/pressure relief outlet on top? If so, it may build 2-4 psi approximately which may adequately serve your first level. I had an OWB and an IGB in the past and operated the OWB without difficulty by: 1) valves on input and output from IGB and 2) valves on input and output from OWB. I operated the system first by turning off the IGB and then shutting both valves (IGB pressure maintained), and second by opening valves on the OWB. I had only a one level house, and the very low pressure from the OWB was sufficient to keep the baseboard plumbing pipes filled without air admission. I used the OWB as the primary heat, and when leaving for a few days I would let the OWB go out; then reverse the valve procedure, and start the IGB.

I don't think this will work on a 2-story house as pressure from the OPB will be insufficient to maintain filled pipes to second level. Then everytime you make the switchover, you will lose some pressure from the IOB to refill those pipes, you will have to add water, and each time you will be admitting air into the system (not good from a corrosion perspective).

One other point. Did you OPB dealer provide you with info and chemicals on treating the OPB water? As an open system, you will have O2 corrosion issues, and you also should check pH and treat as necessary to make sure you have non-acidic water. Ideal pH probably is about 8.5.

Good luck and stay warm.

 

[jebatty]

I seriously doubt that you can pressurize the OPB as it is highly improbable that it was designed as a pressure vessel.

 

[VTVt]

HELLO all thanks for the input. I have spoken with a dealer/user of the boiler who says they have it ground (1st floor) level piped to a basement level indoor boiler direct, no heat exchanger, and claim to be heating two stories above bsmt with no problem.... he suggests moving the boiler to higher ground, so I would be level with my first story as oposed the walk out bsmt level, thereby being 10 feet above the existing boiler.... said i need to have OPB above the heignt of my inside expansion tank in order to not drain out higher levels.... I am still skeptical.... ?

IS ANYONE out there heating more than a one story home without using the heat exchanger? The price for a water to water heat exchanger large enough to push my 250k BTUs and heat my spaces was quoted at $ 1700 ! SOOOO I just went out and drained the OPB as it wont be fired up just yet.

I have only half filled in the 60 ft ditch, 2 to 8 feet deep one end to other, that took me a week of 80% hand digging, and 300 bucks in expenses to dig.... I would have to dig up my pipe and get a truckload of back fill next to my bldg to build up the groundlevel to move the stove closer to the bldg.... I will spend a day digging, a day backfilling and a day moving stove and getting all hooked up again.... and then we will see... I will either be A VERY UNHAPPY person.... or.... success.

ANYONE know ANYONE heating more than one story without the heat exchanger?

THANKS AGAIN!

 

[jebatty]

Typical 12 psi minimum boiler will push water to two stories, and typical hot water boilers operate up to about 20 psi, which will raise water to about 44 feet. if your OPB were about 44 feet above the height of your IOB, it should work fine.

Be careful determining size of HX you need, and the cost. Most on this forum figure a 5 x 12 x 70 plate is adequate. These are about $360 on e-bay. Do your homework; don't take one opinion as the final one.

 

[VTVt]

Typical 12 psi minimum boiler will push water to two stories, and typical hot water boilers operate up to about 20 psi, which will raise water to about 44 feet. if your OPB were about 44 feet above the height of your IOB, it should work fine.

Be careful determining size of HX you need, and the cost. Most on this forum figure a 5 x 12 x 70 plate is adequate. These are about $360 on e-bay. Do your homework; don't take one opinion as the final one.

------------
HELLO, well after months of reading I thought the homework was done, never saw any mention of this issue! SO, where can I get other opinions? The dealer asked a few questions and said that is what I need. HOW do I know?

I saw these for great prices: (broken link removed)
but are they the right kind?

My indoor boiler pressure/water gauge runs at 18-20 lbs of water happily.... I have three stories being heated with this indoor system a total of about 3000+ sq feet, the third floor being about 500 sq feet of that... there are two zones off boiler, and each room has own zone valve.... if any of that matters...

How do I determine size of plate exchanger? Any links?

Besides, who cares if the third floor folks get heat... just kiddin....

 

[jebatty]

You need to do or have done a heat loss calc for the space you are heating, and now others need to help out as to sizing the HX relative to your Maxim250.

Your link is on track. A brazed flat plate heat exchanger is what many use. There are other types, including some homemade ones. If your decision is a plate hx, I would suggest the 5" x 12" (nominal) with the number of plates you need to get your desired heat transfer. You can have more than one and plumb 2 or more in parallel if that works out better than one very large hx. I also suggest minimum 1" inlets and outlets. My preference is pipe thread fittings rather than brazed. Be sure to use unions so that you can remove the hx for cleaning as needed. Also to have isolation valves for the same reason.

5 x 20 hx's also are available, as well as smaller sizes. I would not recommend a smaller size.

I notice from your link that the 5 x 12 x 30 plate is rated at max 350,000 btu/hr. I suppose that's possible under extreme and ideal conditions, but I highly doubt that is the heat transfer you would achieve in a normal boiler operation, with water from boiler coming in at 185 and water returning to boiler at not less than 160. At 10 gpm flow rate on the boiler side, btu's would be 10 x 60 x 8.35 x 25 = 125,250 btu/hr maximum possible transfer. 20 gpm probably is your reasonable maximum flow rate, or 250,500 btu/hr maximum possible transfer. Actual would be less. 250,000 btu's is also the maximum rating for your OPB, and I would be quite skeptical if in fact it actually delivers that quantity of btu's.

Your homework is not done, IMO. And I agree, who cares if the 3rd floor gets any heat?

 

[rowerwet]

according to CB rep and My sisters CB OWB it doesn't mater what level your boiler is at in relation to the loops in the house. I have a CB maxim boiler which is open just like your OWB. CB designs their OWB with just a plastic cap that sits on top of the water tank vent.
It sounds to me like you have a mechanical (taco airscoop or other automatic air bleeder) in your plumbing, probably near the furnace or on some or one of the baseboards. If you do you need to close or remove this as when you go to an open system the bleeder acts as a vent and allows air in. Think of it this way, if you have a garden hose full of water and both ends in a bucket it doesn't mater how hight the middle of the hose is as long as both ends stay in the bucket. However if you put a pin hole in the top of the hose loop you won't be able to keep water in the hose. You have an air leak somewhere.
My sister has a two family house she heats with a CB OWB, the OWB is about 10' below the level of her basement and the floors are above that. She runs an open system which means that the hole on the top of the OWB tank is lower than all of her house. All of her baseboards are actually under a slight negative pressure because of that. The key is to not have any air leaks, remember air will leak in easier than water will leak out. I would gues that you have an autobleeder somewhere or a very slow leak.
You will see water come out of the OWB when you open the valves to the lines that supply it, as you are taking water under pressure and depressurizing it. Your expansion tank will push its normal volume of water out and that will push X number of gallons toward the OWB.
You will also see some water come out of the vent on the OWB as it heats up, this due to thermal expansion, after the first time you get up to temp it shouldn't happen again.
Have you ever noticed a water leak from the FHW plumbing? if not I would look for an automatic bleeder. You should be able to hear the air being sucked into the bleeder as water is coming out of the OWB.

 

[VTVt]

HELLo... thank you for the information. At this moment I have dug up most all the outdoor pex.... 12 feet or should we say $150 dollars worth, will forever remain 6 feet under the driveway as I aint diggin it up again! BUT anyway, I have re-laid two sets of piping (for the two areas i will be heating ) closer to the building and on higher ground. I have a 10 wheeler bringing me about 15 yards of dirt to backfill the holes and to also raise and flatten the area i will now be moving the stove to (there was a small hump/sloped area so needed more soil to be large enough area to hold stove).

After talking to the cb dealer over here they said the stove should be above the EXPANSION tank ..... who knows. I AM DEFINITELY going to go down and check for any air valves as you suggest and close them. I am hoping that this makes a difference. I understand your theory on the PAILS/HOSES etc... I too thought the height of my boiler shouldn't matter. that it should all equalize and hold its own but apparently not MAYBE it is because my expansion tank stands 4 feet high or MAYBE it has to do with open in-line vents.... I guess I will be finding out the hard way!

I figure, if it does not go this time, I can heat the first two levels thru the boiler, and isolate off the third floor (which entails connecting 3 individually zoned rooms onto one loop) and probably add a taco pump to the new loop and put the new loop thru a smaller heat exchanger after the boiler..... so boiler, output to building, but one heat pipe circulates thru a heat exchanger, heats the water on my third floor closed loop system and need a taco pump to circulate .... so then the third floor is on a closed loop so it cant drain out but my already intact zone valves can continue to open and close the heat as needed for those rooms, they just will no longer tie into the main system. I dont know.... still beats another 2k into giant heat exchanger and the loss of heat transfer involved maybe I do not know.

SO We will see.

COST SO FAR DUE TO PLACEMENT ISSUES not so much a big whine as much as wanting to maybe help someone else before it happens to them!
$250 in rented equipment to help open 60 foot / 2-8' deep trench that I do not now need..... $300 in helpers thru it all, the original week of time wasted digging ground for nothing, the original week of personal labor spent digging the now not needed ditch..... the $150 in pipe forever buried 6 feet under driveway....$500 for this week alone in oil burned....$159 for a truck load of dirt, the week of labor to redig out the pipe, fill in ditch, relocate and rehookup the stove..... whatever the guy will charge me coming over with a truck to lift and move the stove tomorrow, the pellets wasted heating whole system twice trying to get it to go.... the oil wasted reheating the whole system when OPB didnt go..... the pellets I will burn to reheat it all again upon rehookup... The two days of labor BLEEDING ALL THE PIPES IN my 3 story 20 plus room building.... DID I LEAVE anything out? can i put a price on the time, energy and stress this has caused? We are talking 2k in true money spent and including my personal labor and time.... all this and I may still need heat exchanger....


Correct placement would have been a 10 foot ditch instead of 60, less pex, no tool rentals that area was dug by hand, a few days of labor not a few weeks, no loss of pellets or oil, no back fill needed, no stove moving, and MAYBE a heat exchanger who knows.... but the 2k would have been total with a heat exchanger not wasted 2k to get it all redone.... stupid.

so question and rexamine and explore all options before placing unit and BE SURE to talk price to go with plan B should plan A not work. I said will my stove work here? sure. What if it dosent? well, get a heat exchanger. NOT known at that time was a heat exchanger to do the bldg correctly would be 1700. OR ELSE the stove would have been placed on hump from day one.

 

[rowerwet]

I bought my flat plate HX off of Ebay, the seller was freeheat4u I think. His price was almost half of my CB dealers price. His listing also had a basic chart of how big of a HX I would need. I got a 5X12" 20 plate, which does everything I need so far. My dealers smallest was a 40 plate and he was recomending a 50 or 70 plate. SO if this is what you have to end up doing you can save some money. Everyone I have read on this site says Ebay HX seem to be ok, at least I haven't read of any flat plate scams yet (give it a min.)
I did a HX install because my baseboards don't have any bleeders and bleeding an open system didn't seem like a great idea to me.
My system has a taco airscoop with the expansion tank hanging off the bottom of it and an automatic bleeder (I think there is spring and a float inside) on top.
Like I said before open works just fine in my sisters house, good luck.

 

[VTVt]

Hi all UPDATE on my system.... OKAY, another week of fuel at $100 bucks a night, TWO loads of dirt later ($250) not one, ton of labor to level the hump on the side of my bldg, and then I had a flat surface at the same level as my SECOND level of my bldg. This time, I once again made sure my inside system was totally full of water, 18 lbs of pressure in my boiler like usual. I then filled my outdoor boiler via a hose outside... I put a bypass on my system inside so I can bypass both or either my heat and hot water, use one or both or none.... so I utilized my bypass and put the circulator on the outside system to fill and circulate the OPB until totally full no air.

OK... then I fired up my outside boiler, letting it just loop thru the bypass... when it got to 100 degrees I shut off the bypass and let it enter my indoor hot water and heat system...... I had opened both my incoming valve to my indoor boiler and them my return valve from my inside boiler to the outdoor boiler... WELL IMMEDIATELY I heard the water going right out, I had a man outside via walkie-talkie tell me YES it was backing out .... SO I IMMEDIATELY - RESTRICTED my return valve which IMMEDIATELY stopped the loss of water.... I left my return valve JUST UNDER HALF OPEN.... this kept the rest of my indoor water from flowing out .... BUT my indoor boiler only read 5 lbs of pressure NO GOOD.... so I left it all running and did the following....

Started on third floor, sure enough no water, SO I sat in bsmt and had another person up on third floor... Via walkie talkie I SHUT DOWN MY RETURN quickly and ADDED WATER to my indoor system via my indoor inlet as I would any other time for my indoor boiler MEANWHILE the guy upstairs bled the line up there and TONS of air came out, and then hot water .... so I quickly opened return just UNDER HALF again (restricted) and shut off the inlet....

By doing this we had the OPB forcing water up and thru and since I shut off the return for just a minute or so, and added water inside, it had enough pressure to bleed the air that got in due to the loss upon turning it all on AND it forced more water in the pipes in the bldg and was able to gain a few lbs....

I did this a few times until no rooms had any air that we found, and in the end I was able to get 12 lbs of water into my boiler! MUCH better than the ZERO I had last time.... well it held overnight and all day....

Although it is not the 18 lbs my boiler usually has, it seems to be sufficient because all rooms are hot and we cannot hear any air.... I MAY do it again every few days to see if I can slowly get more water in the system and keep it there.

SO IN THE END I THINK the MAIN reason all the water came out is that MY RETURN PUMPS on MY INSIDE BOILER are LARGER than the INCOMING pump from the OUTSIDE BOILER...... I have TWO large zones coming back and I think those two 3 or 4 inch pipe sized returns were just pumping the water right out of my system WAY FASTER than my OPB could possibly pump it in.... SO I decided that if I had DOUBLE trying to come out, I needed to restrict my outflow to about HALF.... this would then Equal my inflow..... and therefore would possibly balance out the system so we would not have it all pouring out..... AND IT SEEMS TO HAVE WORKED!

NOW I am thinking of reducing the pump sizes on my indoor boiler returns... they are pretty big... to a size that would still work inside and also in order to reduce pressure going out... then i may be able to open my return a bit more. Another thought is to insert a REDUCER before the return pex... like reduce my 3/4 indoor piping to 1/2 for a short run then into the 1" pex.... this way there is a slowing down/reduction of water flow before the valve... although I am thinking it is doing the same thing as the valve anyway.... BUT it is risky with the valve - if someone opens it too far, water loss will occur instantly.... within about 2 minutes my bldg drains right out... SO if I hardpipe a reducer, that risk is gone.... ??

I am thinking I could have done this when the boiler was on the first level.... restrict the return and would have held.... bleed and force more water in by closing return and adding water inside... but since I found no info about this, it was learn as you go.... I HOPE this saves someone else some trouble.... if you are having trouble keeping pressure inside, consider your return pump and pipe size vs. your outdoor pump size, and slow down the return rate in order to equalize pressure. The 12 lbs I managed to keep so far would do a regular home nicely.... I usually have 18 lbs of pressure but so far 12 is working, even on my bldg.

I have another question regarding temps, but will open a new thread somewhere for that....

THANKS again for anyone offering ideas and solutions!

 

[Plumbit]

This is a great example of way this country is so great, a problem is posed and everybody is willing to help and point us in a overlooked solutions we open our ears and eyes and problem is fixed. Thank you all you tinkers out there you'll solve the countrys problems not our goverment! What we could with the wall street money if it was ours to tinker with in our basement, garages, wookshops etc. God Bless America

 

[JSJAC]

I think that with a non pressurised outdoor boiler and the indoor boiler pressurise you will need a flat plate heat exchanger.That will isolate the two systems.
I went to the dealer in Charlestown Nh and they told me to connect the boiler without the HX . I went with a heat exchanger anyway and it has worked very well for us so far (three years). If you would like I can send you pic of my install inside the house.

 

[harttj]

Vt, I think your missing the point of depressurizing you system. The pressure gauge will read 0 when it is done. As said earlier if there are any auto air bleeds or air leaks this method will not work. I assume some water will come out of the vent on the boiler when it depressurizes and definitely some as it warms up. Don't forget to add enough corrosion inhibitor for the boiler plus the rest of the house that is now susceptible to corrosion.

My CB dealer wanted me to go this route with my Maxim, but I chose to use a heat exchanger and keep the 2 systems separate. It cost more, but seemed easier to me with less risk of issues.

Tim

 

[harttj]

I just saw they wanted $1700 for the heat exchanger! That is way too much as suggested.