Radiant nightmare...need direction

allen h

I would check the output temp of each radiant loop and what the temp is when it comes back. Also what is the floor temperature?

75 k times 2 boilers sounds small for a 5 million dollar house. You haven't given an estimate on sq footage. I think that if you are over 3000 sq .feet that is about tops for 150k btus. You didn't say where you are located. I have 125 k boiler here in northern Mass for 2200 sq foot home, run small apartments between 50 and 80k btus (with no indirects).

I would make sure that the zones to pool and driveway are off. If they are on then the btus are going there.

If you are adding water that is not good. If it were above freezing you could shut down a zone at a time and see if you can eliminate the water loss to one zone.

Good Luck.

Allen in Massachusetts

frank s

radiant nightmare....HELP!

Long story short, went to a total radiant house today, originally installed in the 70's. All loops are 3/4" pex, an example is the 2nd fl. manifold has 8 loops coming off it, how long I do not know, again each loop is 3/4 pex?? it's plastic anyway, old wirsbo system, has a telephone # to europe on a control box. First question is this.... each manifold is fed by 1" copper there are 3-1" lines going to their respective manifolds, basement , 1st and 2nd floor, and 3-1" returns. On each supply in the boiler room are 2 pumps one right after the next, I mean right after one another, is this typical??? Does it help or hinder the system? why is it done? There are no other pumps anywhere in the system, not even on the boilers, which are currently 2 Lennox conservator, 75000btu cast aluminum. Boiler temp set at 140. House originally set up with 2 hydro pulses with solar panels buffer tanks, 3 heat exchangers snow melt pool heat pond heat,frickin everything heat, solar ripped out hydro pulses ripped out, bufferr tanks out, replaced with a Valiant boiler, installer to lazy to change from 2" pvc to 4" so valiant died in a year, now it has these 2 Lennox boilers and the system barely works, if at all, where do I start what do I look for how fast should I run? Come on fellas if anyone can help it's you. Thanks for your knowledge,
Frank

Arthur

Radiant Heating

Hi.
Greetings from NZ, That paradise in the South Pacific.
Point 1) 2 pumps in series are a no-no as the first pump will tend to overide the second and soon cause it to burn out.
2) How is the temperature regulated to each floor zone ?
3) How is the temperature limit regulated to the floor ie is there a 3 way valve or something ?
4) Can you post a pics or a sketch
5) More importantly, Is the owner prepared to spent some dough fixing the problems? If he's not prepared hop on your bike.

frank s

little more info

Hello Arthur, thanks for your reply. The temperature to the zones used to be controlled by 3 motorized 3-way valves, big old ones at that, all the motors are off of them now and they are locked in full open, they used to be operated by a computer that the original owner/engineer built, the computer is also dead. a victim of too much water. The 2nd floor manifold zone valves are all off the manifold, each loop is open. No pics until next week. The owner is willing to spend the money, what's the sense of having a 5 million dollar home with no heat? The previous contractor was ther twice a week to bleed and purge. All your thoughts are welcome. Thanks again,

Frank

Frank_3

Back to basics.

First, I disagree with Arthur about the pumps in series -- it's perfectly acceptable and the result is you can push more water into a high-head zone, and still use smaller, off-the-shelf pumps. The question is whether it's necessary, though with 8 loops off each manifold the answer may be yes.

With only two 75,000 btuH boilers this is either a small footprint house, or it's very well insulated for a '70s era home, or it's incredibly undersized. To put it in perspective, there are three houses on my block (mine included) which were built in the early '70s. Two of them have no insulation in the walls at all, mine luckily did (as an extra cost option, I'm told). The boiler in this house is a 155,000 btuH unit and the house is only about 2000 sq. ft. total (basement and garage included) with a calculated heat loss of around 56,000 btuH. So, my image of the '70s construction industry is that people weren't too concerned about energy conservation or oversizing the boilers.

Back to your problem. A sketch of the existing piping is important. It sounds a lot like another problem house that was discussed here recently, where there were no pumps to move water through the boilers. Go back and do a thorough heat loss as well. If the owners have the pockets then they won't mind taking some time to make sure everything comes out right. Start shopping around for replacement manifolds that have flow meters and balancing valves in them. Figuring out where the current loops go (and how long they are) is going to take time but it can be done.

You've certainly got a lot of work from this job.

Frank_3

Back to basics.

First, I disagree with Arthur about the pumps in series -- it's perfectly acceptable and the result is you can push more water into a high-head zone, and still use smaller, off-the-shelf pumps. The question is whether it's necessary.

With only two 75,000 btuH boilers this is either a small footprint house, or it's very well insulated for a '70s era home, or it's incredibly undersized. To put it in perspective, there are three houses on my block (mine included) which were built in the early '70s. Two of them have no insulation in the walls at all, mine luckily did (as an extra cost option, I'm told). The boiler in this house is a 155,000 btuH unit and the house is only about 2000 sq. ft. total (basement and garage included) with a calculated heat loss of around 56,000 btuH. So, my image of the '70s construction industry is that people weren't too concerned about energy conservation or oversizing the boilers.

Back to your problem. A sketch of the existing piping is important. It sounds a lot like another problem house that was discussed here recently, where there were no pumps to move water through the boilers. Go back and do a thorough heat loss as well. If the owners have the pockets then they won't mind taking some time to make sure everything comes out right. Start shopping around for replacement manifolds that have flow meters and balancing valves in them. Figuring out where the current loops go (and how long they are) is going to take time but it can be done.

You've certainly got a lot of work from this job.

Frank_3

Back to basics.

First, I disagree with Arthur about the pumps in series -- it's perfectly acceptable and the result is you can push more water into a high-head zone, and still use smaller, off-the-shelf pumps. The question is whether it's necessary in that particular design.

With only two 75,000 btuH boilers this is either a small footprint house, or it's very well insulated for a '70s era home, or it's incredibly undersized. To put it in perspective, there are three houses on my block (mine included) which were built in the early '70s. Two of them have no insulation in the walls at all, mine luckily did (as an extra cost option, I'm told). The boiler in this house is a 155,000 btuH unit and the house is only about 2000 sq. ft. total (basement and garage included) with a calculated heat loss of around 56,000 btuH. So, my image of the '70s construction industry is that people weren't too concerned about energy conservation or oversizing the boilers.

Back to your problem. A sketch of the existing piping is important. It sounds a lot like another problem house that was discussed here recently, where there were no pumps to move water through the boilers. Go back and do a thorough heat loss as well. If the owners have the pockets then they won't mind taking some time to make sure everything comes out right. Start shopping around for replacement manifolds that have flow meters and balancing valves in them. Figuring out where the current loops go (and how long they are) is going to take time but it can be done.

You've certainly got a lot of work from this job.

Boonierat

Radiant nightmare

Frank:
I must agree with Mr. Sapienza. Two pumps in series is unusual but is done when you need to overcome higher T.D.H. (read that as 'resistance'). I've spec's that on rare occaissions. Put the same pumps in parallel when you want to increase the G.P.M. if someone did that in the past he/she may have thought they had a real good reason to. Tough to second guess that. Look for what that 'resistance' might be. Real long radiant loops, mixing valves, lots of fittings are typical culprits culprits. In-series pumps are unusual but acceptable. Love to see a sketch or pic's of this sweetheart

Chris Maderia

Where to begin

We need to start with a whole bunch of questions. What are the complaints from the customer? Do some rooms heat and others don't? Does this only happend when it's real close to the systems design temp? What's are water temp running in the floors? What are are surface temps? There are a millions questions. You need to take baby steps on this one. Take it slow and 1 step at a time.

Dale

Good news is

You can probably save this system. 3/4 pex should be more than big enough for any of the inside loops, and it is pex. This should be a T&M job until you figure where every thing goes and how much insulation you have. If they will pay your normal hourly design rate plus site travel it sounds good. Then a bid to make it right. I would temporarily put flow meters in all the loops and run them with a 007 I'll bet the flow is really high. Then you know that you can primary sec design this with separate loop pumps. Perhaps the heat loss will show the need for a buffer tank and I wonder what kind of a heat exchanger the snow melt uses. If the pex is good and not leaking you should be fine, if you want to be really safe isolate all the loops and lay an air test on them, I'll bet they are Ok.

frank s

Thanks and keep it coming

Thanks for all the replies and please keep them coming, I'll take some pics of all the piping next week and post them as well as measuring the house for a heat loss. The house by no means has a small footprint, I would think about 4500 sq.ft if not better. Thanks for your time and knowledge,

Frank

Arthur

Radiant Heating

Hi,
Sorry but still stick by my comments on pumps,
1) I've seen pumps in series before too, and I've also seen them all burn out sooner or later because the first pump overspeeds the second pump. If you have to put in two pumps go and buy a bigger pump to do the job properly. Less work, less wiring, less plumbing, less hasle, and it's the right way to do it and cheaper in the long run.Two pumps in parallel are ok if they both have check valves on the outlet to prevent one pump bypassing back though the other. Commonly done were it is essential for operation like in a hospital or such.
2) Sounds like you need to reinstate a new control system to control the 3y valves with sensors (not thermostats in the areas controlled)to modulate the valves.
3) Why did the other contractor have to bleed the system once a week ? Hope it wasn't sucking air into itself. Perhaps these two pumps put too much 'suck' on the system ? Air will cause extraneous corrision in the system if left for too long.

frank s

Maybe Dave Yates........

Could give me his opiniion, This kind gentleman is a man I highly respect, whaddya say Mister Yates??? Excuse me, I mean Dave...........don't want to make you feel too old. What are your thoughts?

Frank