Welcome! Here are the website rules, as well as some tips for using this forum.

# 700 foot loop.

Options
Member Posts: 396
The house is almost ready for paint. The tube was instaled by the gc. The architect asked last week who was designing the system. She was not happy with my answer so they asked me to look at the system. Most of the loops are about 400 feet. The top floor is almost 700. I looked it up. I can get a bit over 1 gpm with a 26-99. But it scares me. I like 250-300 foot loops. Its in a San Fransisco house with no crawl spaces and its on the top floor so adding loops woild be a big deal so they are fighting it. Input?

• Member Posts: 1,013
Options

the loop is servicing.

is it one room or several?
Rob Brown
Designer for Rockport Mechanical
in beautiful Rockport Maine.
• Member Posts: 5,853
Options
You could use a 4 way reversing valve...

Every 10 minutes or so, the 4 way reverses the direction of the water flow through the tube circuit. It would require you to use a zone valve that doesn't care what direction the water is flowing (White Rodgers or Taco ball).

Did anyone bother to do a heat loss calculation?

ME

There was an error rendering this rich post.

• Member Posts: 9,546
edited February 2011
Options
I don't understand

When someone makes a blunder as this. The GC needs to redo it at his expense since he did it. To bad if its not ideal tear out redo circumstances. Money hurts, and teaches a lesson.  Evidently the architect knows something is wrong that is why you are there. This would teach the GC not to dabble in something as easy as hydronics (at least he was thinking that).

Yes Mark has a solution that works which is more parts, controls, valves etc, and time to fit components to make it work. But in the end is it as good, as it could have been if done right, definitely not as efficient. One 700' loop for one floor. Some rooms are going to get the long (cold) end of the tube. Not like its snow melt.

• Member Posts: 4,106
Options
Long Loop

What is the diameter of the tubing?
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

Two btu per sq ft for degree difference for a slab
• Member Posts: 396
Options

and I agree the GC should just pay to do it right. However he is a potential new client and I want to work with him as much as possible. At least I can give him the cheaper option with the disclaimer that it is far from the best and he should open the walls as much as necessary to do it right. He will say no but I will put it in writing.

So the area in question is two rooms and two bathrooms and the top floor stair landing. The heat load is low. with out a load caulc. I cant say for sure but the homes in San Fransisco tend to be long and tall. So in this case the long sides of the house are in contact with the neighbors and the short ends are the outside walls. The only other load is the ceiling. The walls and ceiling are newly insulated just the old windows remain. Almost every home in the city is considered historic so you have to remove re-glaze and replace the windows . It does not happen very often in San Fransisco so the old drafty windows stay. That said in homes like this I usually come up with about 10 to 18 K BTU for the top floor. Its about 1000 square feet.

Tube is 5/8"

I like marks idea from a fun to build stand point but I would rather not leave that for the next service call. I did a bit more research and I think I can use a 26-99 for the two circuits for that zone and get it to work OK. luckly the loops run out to the outside wall and work back to the interior.
• Member Posts: 9,546
Options
5/8 tube

At least its not 1/2, or 3/8.  That was a thought of mine also is the next guy that has to do something to the system.  Will they have a full understanding of what the set up is trying to accomplish. I'm sure you would leave detailed info.....but then your name is on it. Guess what that leaves the next guy thinking. Another thought is the reliability of the reversing valves. Mark would know, I have read quite a few threads here of long loop blunders he has recommended this set up for.

I guess I just view hydronic heat as being as simple, and elegant as possible. When you start making the system like a mechanical room for a high rise I have to think it scares a prospective homeowner as to the possibility of parts to break over time. With FA they see a box everything is contained in, and most can change a filter. If it stops working they call the tech he goes to the box to fix it. In no way am I advocating FA with my statement just outlining a homeowners frame of mind.

Gordy
• Member Posts: 5,853
Options
Definitely a band aid fix...

I hate having to deploy it (the 4 way reversing system), but it does work in a pinch. I'd make the HOMEOWNER aware of the situation, and have them make the decision. The GC is probably the responsible party, but as has been expressed, it is an expensive lesson that needed to be learned.

Wonder if he yanked the insulation package out of the suspended floors as well....

I hate being pessimistic, but have been there and seen that mentality. "This ain't rocket science. Anyone can do it 'cause I read about in on the internet".

WIll, are you SURE you want this GC as a client?

GC world is just like ANY contracting business. 90% of the people who are in the business don't have any basic business acumen, and have no idea what their direct costs are, and their idea of making money is based on cutting corners in the course of construction. They price themselves at what they feel the "market" will bear, and make money off the backs of their sub contractors.

Keep this in mind in your dealings with the GC. He doesn't have YOUR best interest in mind, only his own.

ME

There was an error rendering this rich post.

• Member Posts: 396
Options
I was hoping

that someone had found and solved the same problem. I have also seen a few threads go by about long loops. I know the four way valve would work. I keep re running the numbers and it looks like I can run over a gallon and a half a minute with a 26-99 and this does not exceed the velocity that the pex can handle. Regardless of how it looks on paper it makes me nervous. That is the best thing about this site the fact that I can bounce this off some people makes it a lot easier to sort through.
• Member Posts: 1,013
Options
personally

I would consider the one loop for multiple rooms unacceptable, and without a load calc I definitely would not guarantee any kind of specific comfort results.

with 5/8" pipe and a big pump the problem probably won't be flow, in san fran. but relative comfort of the two rooms, that's another question.
Rob Brown
Designer for Rockport Mechanical
in beautiful Rockport Maine.
• Member Posts: 9,546
edited February 2011
Options
Well Said Mark

"WIll, are you SURE you want this GC as a client?

GC world is just like ANY contracting business. 90% of the people who are in the business don't have any basic business acumen, and have no idea what their direct costs are, and their idea of making money is based on cutting corners in the course of construction. They price themselves at what they feel the "market" will bear, and make money off the backs of their sub contractors.

Keep this in mind in your dealings with the GC. He doesn't have YOUR best interest in mind, only his own".

Now that comes from someone who has dealt enough to know, and so true. In my realm of construction its the same thing.  Sometimes my company gets to play GC, and sometimes they are the sub. Whats interesting is its the same circle of companies taking the GC slot, or  Sub slot.  Its just a matter of sending each other the jar of vasaline in the mail. Along with the extra work orders, liquidated damages bill, We are not paying you for this bill. You did this to us when you were the GC so here it comes back in your face. We will give you this part of the contract if you bid it as such then they give it to someone else. I think they enjoy it I really do.

Whats sad about it is it really makes it hard for the people trying to work together in the field to get the job done.  Things like you can use my back hoe, so you dont have to haul one in for 2 hrs, and I need some stone can I use one of your trucks done deal. Then the Project Manager shows up.

Sorry to high jack, but Mark struck a valid note.

Gordy
• Member Posts: 396
Options
it is in the back of my mind

However I will price the jobs to do it right. with that in mind if he does not accept my cost he can go ahead and do it himself again. However to his credit his plumber who works for him as an hourly employee told him he new how to do it. So the GC should have done more than take his word for it but the plumber obviously had no idea how to put it together. at this point he cannot be reached. The helper that worked with him is still working the job though. this contractor does his plumbing and carpentry in house and subs everything else. Although the plumbing may not be in house anymore.  I am concerned about not being able to balance the individual rooms this and other concern are going into a letter about the issues with the existing system. I do intend to incourage him to open the walls and do it right.
• Member Posts: 2,398
edited February 2011
Options
Visualize

Just chiming in. I was thinking about what Mark was saying, regarding the reversing 4-way valve approach, which I liken to the tides.

But also, looking at the positive factors: 5/8" tubing versus smaller sizes as Rob noted, narrow end exposures and relatively low heat losses.

As we call can imagine, the heat losses are at the "short ends" diminishing toward the interior. Assuming the roof is well insulated (or can it be? If so, it should, it must be), success is within reach, using the reversing 4-way but possibly, depending on how the tubing was run, without it.

The question I have is, do you know how the tubing is laid out? If it starts at one end exposure and in a serpentine fashion across the width, ends at the other, the reversing 4-way is a good -if not the only- approach.

I may even suggest within this, a dual control approach. Warm up for the day with a back and forth flow and when the sun hits the sunny side (is there such a thing in SF?), the shady side gets priority control as the higher demand. One thought.

The best situation overall would be if the tubing started and ended in the middle. Supply heads to one end, back and forth the long way, end to end for even coverage, that could be quite even in temperature. If "uneven", that would be across the width, not one end versus the other end of the floor. if that makes sense. A reversing 4-way valve may not be needed or would be of less benefit in this case. Hoping!

But as Mark and others have suggested, the reversing 4-way valve approach is a band-aid, the best thing one can do for a bad situation.  That you can get 1.0 gpm for what may be 18 MBH is a 36 degree delta-T. Can we reduce the heat loss any more? Talking cutting it in half here. Windows. Do something.

There is no real substitute for "the right way" (or "right ways", plural, for there is a range of good practices).

The obvious lesson here is that the lack of planning, knowledge and experience (or rather, not knowing what you do not know), has a ripple effect across all trades and eventually, energy cost -high pumping costs- and  lost comfort for the life of the system.
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

• Member Posts: 1,468
Options
5/8" PEX at 2 GPM.......

.......and 120 degree water, a 700' loop has about 31' of head.  A Taco 009 will overcome that.  So, at a 10 degree drop that's 10,000 BTUH.  I've seen worse.

There was an error rendering this rich post.

• Member Posts: 4,333
Options

DO you really think this gc will hire you knowing now that you know he is not on the ball. I find most GC's like their subs to be dumb enough to take the fall when the GC makes a mistake. DO what you know is right and at least the Architect and Home owner may recommend you to future clients.
Cost is what you spend , value is what you get.

cell # 413-841-6726
https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
• Member Posts: 9,546
Options
Doable

Maybe....Right no.  Probably paying a good dollar to boot, especially with the possible mods.  This is what gives hydronics a bad name, and FA the edge even though they can butcher that too. Sure the knowledge here can make it work, but is it how they would do it to begin with? No.

I do not know if this is a spec home, or a home designed for a buyer, but I sure would not pay top dollar for a Cadillac that is modified because it came off the assembly line jacked up, and it will run but not quite like one that came off the line as it should have.......Would you?

Gordy
• Member Posts: 1,468
Options
I wholeheartedly agree, Gordy, but.........

.....trying to get the GC to fix this is, in all reality, probably not going to happen.  If he does agree to pay for the repairs, that would be great and I suppose stranger things have happened.

Will, if the GC mans up, realizes he screwed up, and does the right thing, he may be worth quoting the next project for.  But if he tries to shift blame, which they often do, then show him the door.

There was an error rendering this rich post.

• Member Posts: 396
Options
He has

We are doing another project for him. Its a complete remodel with three zones of radiant heat and domestic hot water indirect. He did not say a word about my price either.  I am having a meeting with him and his partner on Monday about the hous4e with the long loops. Who knows he may fix the tubing. I told him my mechanical is over a grand more than it would be due to the extra pumps instead of zone valves with one pump. I am hoping that entices him to open some walls. Also I would guess the homeowner has no idea what is going on. I did send him a e-mail explaining the potential problems with the tubing layout. so he cant play dumb or point the finger. Thank God for e-mail.

Final note; they used the black clips that suspend the tube from the sub-floor. They did insulate with reflective backed R19 and they did leave a airspace. but the temps are not going to let the boiler condense much.
• Member Posts: 9,546
Options
Good move

CYA before someone Covers theirs before you on their own terms.  I'm sure homeowner will appreciate this not so much the GC though.
• Member Posts: 2,774
Options
They need to fix it right!

To put a bandaid at best on a new system when the house is not finished is a sin. They need to open up and deal with it. A lot cheaper than doing it later. Which they will probably have to do anyway.
This discussion has been closed.