Heat Loss calculation discrepencies

Mijola

I agree

WPH2250,

Per my post above, I too think that Frank has more than one problem. That is why I asked the various questions about the other rooms on the zone,(re length of overall zone) possible zone valve instead of a dedicated pump,(re shared or reduced water flow to that zone),location of stat (other rooms on that zone satisfied before great room), etc. We need more information from him, to really sort this out.

HEY FRANK, ARE YOU STILL THERE?????

Regards,

Ed

frank_32

sorry guys. yes i'm still here. i am not only researching this here but am also trying to get it worked out with the contractor. PLUS i have a new addition(baby boy) to our family as of the 14th and we are still adjusting. ie...not much sleep at night.

i know that the kitchen/dining room and the living room all run off the same pump if that's what you are asking. i know that there is an 8' bb in the dining room, a toe-kick heater in the kitchen(equiv. to 8' bb) and then there is 33' of bb in the greatroom. the house is set so the front windows in the greatroom are facing the south. there are two standard windows and a man door on the longest outside wall(east wall) and then there is only 1 skinny window on the west wall which also is the wall that has the stairs going up to the loft. picture the house as a rectangle 26'X 38' with a 16'X 24' attachment to the west long side. the small rectangle is my master bedroom, bath and walk-in-closet. then above my room is a bedroom with a high pitched ceiling. the main body of the house looking down on it as if its a flat piece of paper, has the greatroom in the bottom, then the kitch/dining room on the top. then on the floor above the kit/din. room is a bedroom, bath, and walk in closet. i hope i have not confused anyone.

i really appreciate all the responses. i feel overwhelmed with all the information. i met with the contractors new heating guy. when asked if he was going to do a heatloss calculation for the house, he responded he already did at the contractor's office. he advised that there is adequate baseboard througthout the house. when asked about how he came up with his calculations he advised that he used the tried and true method of cubic feet of the room X 2.5=btu loss. i was floored. i asked if he factored in the large amount of glass and the cathederal ceiling, and he said that its tough to figure them out. nice guy but i just don't get it. he stated he doesn't use a computer program or anything because it would probably get him in trouble. i don't want to sound cynical or critical but that to me is not very professional. if the technology is there then use it.

i spoke to a heating rep from a local supplier later today and he sounds like he has his ducks in a row. i asked for him to complete an entire house calculation room by room. he advised he would and would provide me with the printout. so now i am going to gather all the necessary info and get it to him. so hopefully we get everything cleared up soon.

everyone here has been a great help. i really appreciate all the responses. my only goal in this is to make sure my house heats as it should. if the original heat rep's calculations stand after this latest guy compeletes his calculations then I'LL admit i was WRONG and move on.

thanks again.
ray(also known as frank)

Dale Pickard

Right on

I think you are right about this Gary. It looks to me like this guy is wanting to put as much as 60 btu/ft2 to this room. That's a lot of heat. I "high" heat loss room in new construction might be 35 or 40. The variable most likely to affect this is air leakage. If the room really has a heat loss rate that high, then the problem is with the room. It's not responsible to always just design the heating system to be capable of doing unreasonable things.

Tell us about your blower door service, and thanks for the links.

Dale

Dale Pickard

Forget the heat loss calculations, the room is built. If the baseboard that you have in there will not heat the room then the problem is the room. You can add enough baseboard to heat the room at 60 btu/ft2 and the next thing you will be complaining about the energy usage.

Look for air leakage, read Gary Wilson's post above.

Dale

GW

yes, the building is up

In hydronics, we can get away with lots of stuff, lots of guessing and come out smelling rosy. Once in a while, like we all discussed on my "outdoor rest, customer not happy", AND on this post, things backfire and we have to go back and scratch our heads.

Someone asked in this post if there were recessed lights; I don't believe there was ever an answer.

I'm looking at an AC job right now where the guy has 5 tons in a 4500 or so sq ft house. Another ac guy told him he needs another 3 tons. I asked "did the guy measure out the house?" the answer was no.

I said, "Well let's see if we can't keep the 5 tons; let's see how leaky the house is, how leaky the ducts are, and we'll see if we can make the house comfortable with the 5 tons you have now.

Bad duct work can bring huge losses of efficiency. Sadly, this is poorly regulated, or maybe I should say not regulated at all in Massachusetts. I believe this will change slowly.

Anyways, for all of you heating guys out there, you may want to indicate on your proposals exactly what 'air change per hour' you designed your system to operate at. If there's a problem you'll be covered. If you don't indicate this you'll be on the hook to 'make it right'. Without a blower door, you'll never know what the infiltration is. Don't even try guessing if you're experiencing problems; air will enter and leave the building at the most peculiar places. I'll explain the blower door process in the next reply

Gary

GW

blower door

We got involved with blower door testing last year. It was an expensive process, but we can do thing no other hvac guy in our area can do now.

Also on sales calls it helpful for the same reason mentioned above. Like anyone else trying to make a living, I'll use this tool to it's fullest potential. "Oh, this is simply to see how tight, or how leaky the house is. Without this tool, I would have to guess" Usually, people don't want to hear the word 'guess'.

It takes about 5 minutes to set up. My only struggle is how much room it takes in my Explorer (it brakes down into two cases or bags, and the third bag has all the diagnostic items, cords, smoke puffer, etc.

There is a 8 minute or so video that is on my lap top for the home owner to view as I'm setting things up. So, credibility is being built for me, and taken away from my competition.

I spent 5 days learning about this in December, so it's hard to lay out all the details in one post!

Gary

Constantin

You're on the right track, Gary!

I hope that we see the beginnings of an evolution in the heating business where smart contractors like you are rewarded for their investment in time and equipment. It's an evolution from being only responsible for the bare bones of a heating and cooling systems, to becoming a a comfort technician that can address the whole picture inside a house.

Just as CO-meters and other equipment had its detractors, so will the blower-door test.... that is, until everyone wakes up to the business opportunity these doors represent. How much more valuable are you to a homeowner when you can offer options besides yanking a boiler?

Anyway, I hope other homeowners are/will be as excited about this technology as I am.

frank_31

there are no recessed lights. as for the comment about complaining about energy usage by dale... how's this for energy useage? the system was fired up with propane in the first few days of dec. 04. i have an outside wood boiler with a heat exchanger plumbed into the return line to the propane boiler, that is now the primary heat source as of 12/10/04.

i have since used 9 FULL cords of hardwoods(maple, beech, oak), 1.5 ton of coal, AND 250 GALLONS OF PROPANE. my house is 2000sqft. and during the coldest stretch of winter in early jan. the greatroom zone, master beedroom zone, and basement zone ran constant for 10 days straight. only reaching 64 deg in the greatroom and master bedroom. thats unacceptable. so thats what started my quest into the problem. anyone else think there's a problem.

i questioned the heating salesman's calculations only after researching the possibility of there being a problem with his findings. it's nothing personal i just want my house to heat adequately. i can't see how the system should run for days at a time when the outside temp is in the 20's and not reach 70 deg inside.

thanks again for everyone's time.

ray

Brent_2

i agree

I would definitely go with the 3 ton. Especially with 2 stage and especially since it is the 2nd flr. You will get a decent amount of heat drifting up from the 1st flr. Being a little oversized with a 2 stage unit won't really hurt you. I am surprised to hear someone actually makes a 2 ton 2 stage unit. I wouldn't think there would be much demand for it.

brent

Dale Pickard

You're pulling our leg(s)

No way you can put that much heat in a 2000 ft2 house in a few months. There's something wrong with your house your system or both.

Dale

frank_31

Dale,
That's what I am trying to figure out what the problem is. I feel that they under baseboarded my house so the system runs constantly for days to get it up to temp and only after a nice sunny day is the house up to temp. It is really frustrating. I am paying to heat a house I do not even live in yet. I have over a thousand dollars in heating the house and am getting no help from my contractor. I have done all my own research and have suggested several things to them only to have them blow me off. Believe me this heating stuff is interesting but I would rather leave it to you professionals than try to learn all about it so I can fix my own system.

Ray

Dale Pickard

OK

Sorry for the cynicism.
A good rule of thumb is that a reasonably well insulated home in a northern climate in the U.S. might need any where from 20 - 30 btu / ft2 of floor space. If you suspect that it may not be built that well or insulated that well, you might figure more on the 35-40 range. We look at leaky log homes and judge them in the 45-55 range here in Montana. Air leakage is a major variable.
One foot of baseboard will put out 500 - 550 btu/hr at 180 if the damper is open.
So 2000 x 30 = about 60,000 btu/needed to be delivered for the house under design. 60,000 / 500 = 120 feet of baseboard should heat the entire house under design conditions with 180 deg water.

I haven't put the numbers to it but your fuel use seems very high for just a few months though bear in mind that fuel use is higher for a new home until it loses some moisture and that it will be a little higher if no one lives in it.

There are a few ways that your heating system could be screwed up to use extraordinary amounts of fuel, but usually it's the opposite. Screwed up systems don't run much, hence they can't use much fuel. It's hard to burn a lot of fuel and not have the heat show up somewhere.

Also, remember that on sunny days there are good passive gains available and the heating load is low because the outside air temp is high. How does it do on the night after sunny days.

I hope that your wood boiler is plumbed and controlled in such a way as to prevent the gas boiler from operating when the wood boiler is producing sufficient heat. Also the gas boiler shouldn't be allowed to put heat into the wood boiler, especially one of those outdoor ones.

Why don't you take few photos and share them with us. Photos of the system and of the house. If you have any design information on the house or the heating system then please share that too. You can send them directly to my email address or post them here on the wall. You can call our offices here and ask to speak with one of us. Ask for me or for Brian. We don't mind helping you figure this out. I don't think you need more baseboard, but since you mentioned the outdoor wood boiler, I suspect that it's quite likely that your controls and piping and control strategy are screwed up. Do you also have a storage tank in this system. The outdoor boilers are open loop systems..... where are the heat exchangers in your system?

Dale Pickard
President
pick@radiantengineering.com
Radiant Engineering Inc.
501 E. Peach
Bozeman MT 59715
406.587.6036
406.587.1617 fax

Steve_35

This is a room with

HUGE amounts of glass and a 20' cathedral ceiling. Frank (Ray) mentioned 75% of a wall of a 20' x 25' being glass. He doesn't mention which wall or if it's an eaves or end wall but you're looking at about 30% of floor area in glass at a minimum.

I recently quoted a job and the owners would like to use radaiant. The home faces a lake. One whole wall of the home is glass. Lots of skylights. This is a new, tightly constructed home in upstate NY. 45btuh/sq ft loss.

Most of the new homes we see are in the 20-30btuh/sq ft range same as you're seeing, but lots of glass and skylights will drive that number up in short order.

The ironic thing is now the job is coming in high (wow is that unusual or what) and one of the first things they're looking at cost cutting is moving from radiant to FHA. I hate to think just how uncomfortable they'll be in their beautiful new home.

Weezbo

let me \"share\" with you a momment....

Sunday, my buddy a senior of about 8 10 years and i went to look at a place in the hills...it is a very sad situation for the home owner. It has two cabins,Log, both with garages..it has a 115 buderas mounted on the largest buderas residential water maker the guy could buy...the boiler is lashed up with zero idea of what it is supposed to be doing :)the wiring and DWV looks really pz poor. unfortunately a heat loss was never even suggested till i dropped in on the job. and it was seen by quite a few other contractors...like you ,it will be eating their breakfast ,lunch and dinner for the rest of thier lives...the minute someone touches it they bought it..they the Habby Home owners have a Hit list of things to do..a blower door test er...thats not even in the picture, a heat loss?? whats That? additional supplemental heat? "er..nah we have a "seperate zone" for that bath room..."(of which there are 7 )any consideration given to and HRV?...as this is a rather unique and somewhat atypical designe? "what do you mean by that?"the wirsbo he pex(one good point) is all different kinds of lengths and the loops come out of the first floor slab all over the place nothing how we say "Together" piped on a phylosophy of full time employment, or career, maybe... even live in plumber...the boiler is having like 100Kbtus thats it....well the second floor and third floors have other minor technicalities not the least of which the three story of glass wall is going to put balancing this system into a miracle a weee bit larger than i am normally asked to preform....the home owners are thinking of going into business as a B&B for tourists...their most important consideration is hooking up the floor heat...i hate to tell themthe bad news...so in my opinion even another boiler wont satisfy the heat loss.this isnt totally unusual for homeownes playing General contractors..they have alot of Quality built right in and there are going to be qualities that cant be built out...i honestly see the word Liability Printed all over this place....when we walked in i could hear the boiler running,...many contractors have been invited to come to "Look it over" soon as we pryed the garage door open and i "libmoed" under the half open door i could hear the boiler begging me to allow it to breathe...so i pulled the box off the riello and mentioned that he needed to clean it from time to time and to take it away from the boiler and bang it on the floor and take the vaccume cleaner to the thing as it needed to "Breathe" like us ...this isnt thought out correctly at all...the details that have all kinds of attention are wonderful and all its just the other minor technicalities as it were....the people hosed thier own dream as it were...so i have to pass on the "Opportunity" of the contractor leaving town on vacation ...you see, i own my own home and helped build this community...people can hand all kinds of money to some clowns who hand them all kinds of wrong way charlies.. y, who knows?..fixing this one isnt going to be comming in "Light " at all. and quite honestly, i dont have the time to sidewalk engineer this thing back on track at the momment.

GMcD

All that glass

And I bet no one has figured out what the radiant cooling effect of that glass is in winter. Even if all the baseboard was correct for the skin losses, the interior surface temperature of conventional double pane glass at an outdoor temp of 10F with baseboard under it will average somewhere around 56-60F on a good day. That provides a radiant cooling effect of about 30-35 Btuh/SF of glass surface. That's a heat loss that doesn't get calculated in all the normal commercial software because they are all built on inatantaneous heat losses using "air temperature" as an algorithm. In a room with that much glass, the mean radiant temperature will be, say, 65F if the walls and floor are warmer than the glass. With an air temperature of 77F, the "resultant temperature" (what the human body actually feels) will be about 71F, and will feel colder the closer to the glass you get.

It's all about the glass. If people want to have huge expanses of glass, and they choose to use conventional double glazing, they have to sacrifice energy costs, comfort and capital costs for the mech and elec systems to compensate for it. For the life of the house.....

Have a look at some of the suspended film high performance glasses like Heat Mirror. 1/3 of the heat transmission, more solar gain control, yes at a cost, but then the mech and elec systems are downsized, and on-going energy costs are reduced, and comfort is vastly improved. Easy.

frank_31

no problem with the cynicism. I am just getting frustrated beyond belief with this whole mess. I have not heard from the contractors in about a week. They were to come in on monday and "fix" all the problems with the system but pulled their new heating guy when they heard that i hired someone to recalculate the heat loss for the house.

the house is currently heating like a champ. the outside temps have been in the 70 deg range the last few days here(much needed to boost local morale). the inside temp of the house is roughly 80-82 deg throughout the house. there is not one zone calling for heat but since they hooked up a bigger primary loop pump, its seems to be pushing this hot water thru the zones all by itself. infact the hot water maker(domestic hot water) is on its own zone and is set on the lowest setting since we are not living there. i wanted to test it to see how high i had to turn it up before it kicked on the zone pump. i was able to turn it all the way to high and the zone pump never kicked on. the water is being heated to the max temp without the heater even calling for hot water. the entire house is unbearable.

i am at work right now and do not have any pics of the house. as soon as i get a chance to post some i will. i know that i had actually posted some of the dunkirk boiler and plumbing off of it before.

the outside boiler seems to be working like a champ. the problem is that when it's cold out the house is constantly and i mean constantly calling for heat, so the wood boiler never gets a chance to take a break. the original problem with the system was that the heat exchanger was plumbed in at the end of the return line before it went back into the dunkirk boiler and there was no primary loop pump. infact there was no real primary loop since it was obstructed with the mixing valve for my radiant heat in my basement floor. so when a zone called for heat the water had been sitting idle in the dunkirk boiler and when it kicked on it had cold water in it so it fired for about 5-10 mins at a time. so everytime the system kicked on it would burn propane until the water was moved thru the heat exchanger enough to heat the water to the high limit.

we have since replumbed the mixing valve and put in a primary loop pump. the first primary loop pump was a taco 007, and it was believed that it was too small to pump the water thru the heat exchanger, so it was upped to a taco 011 at the direction of dunkirk. it was then realized that the 011 location was causing the return water from the zones not to go back into the primary loop(011 was placed just prior to the return manifold) and would sit idle in the secondary lines, cooling the house to 58deg. so they moved the primary pump to the opposite side of the return manifold but now we are at the point where the primary pump is moving all that water thru the zones when they are not calling for heat.

i cannot remember the exact amount of baseboard in the house but i know it was in the 70-75' range and no more than that. And 33' of that is in the greatroom alone. that is why i am having this other guy re calculate the heat loss. the original guy's results just did not jive with the recommendation of the weil-mclaine rep, my own quick calculation on the internet, my calculation using slant/fins program, their own plumbers calculation, or the calculations of two other heating guys. they want to blame shift everything.

hopefully we can get this all resolved peacefully soon. i am sick of visiting my completed house for a couple hours at a time then going home to my apartment. and also paying a mortgage and rent, along with double utilities. i hate to complain so much but this is really aggravating. thanks for the assistance everyone. unfortunatley some of you are talking about things that are WAY over my head. but i still appreciate your input because as i learn more and more about this i can then understand what you guys were talking about.

ray

Dale Pickard

Screwed up

It sounds like a truly screwed up system. The 011 puts up enough head to open your zone valves. A system for a house your size should never require a pump like that. A differential pressue bypass valve may be appropriate, but I suggest some system redesign and repiping. It sounds like your contractor is just an experimenter.

When you talk about boiler or baseboard sizing and design heat loss calcualations you have to realize that we are talk worst case conditions. You say your system is only capable on sunny days. The worst case only occurs for a few nights a year. So your system or house is more screwed up than just not enough baseboard.
Post some photos.

Dale

frank_31

frank_31

here are some pictures of the heating system as it was originally plumbed. it has since had the primary loop pump installed. first it was placed just prior to the return manifold then moved to just past the manifold and before the heat exchanger. also the mixing valve has since been moved. i will try to get recent pics up when i get a chance. these were previously posted here during one of my other posts.

ray