Balancing a Variable Speed Injection Radiant System

I am having trouble balancing a Variable Speed Injection Pump In-Floor Radiant Heat System.

A few weeks ago I had my home half heated by a propane Renei forced hot air unit, and half heated by a in floor radiant heat. Now I have 100% in floor radiant heat, but the techs that came out to help add the new system into my boiler knew little about this method of radiant. Yesterday I hired what I thought were much more educated techs to help balance the system better only to find out they knew very little either. The senior guy said that no one is installing injection radiant floor systems in any more which I thought was strange because he went on to say that most radiant heating systems work too well and are too hot. Well my understanding was, that was the whole reason for the variable speed injection...it keeps the home warmed based on degree days, heat loss of a building, expected coldest temps, etc. So is he right, this is an antiquated system?

They wanted to crank the water temp running through my concrete slab to 120 degrees and simply let the thermostats and zone valves handle the control. I was leery of that, but currently my boiler cannot quite get the temp in the house past 68 degrees when it is set on 70 degrees even if it is fairly warm out. Don't get me wrong, it does not drop to 54 degrees when it is cold out, it just stays at a steady 68 degrees. I did set the Inside Start Temperature up a bit hoping to get a little warmer water flowing through my floors, but it will be a bit to see if that works as with in floor radiant, it takes a bit to see a measurable change in the slab temperature. I certainly hope I did not screw the other temp settings of the TACO 705-2 controller up by not messing with them!

So which theory is conserves the most propane: use high temp water controlled by thermostats and zone valves to heat the home but end up with wide temp swings, or

Use degree day theory to heat the home via varying the water temp flowing through the floor to account for heat loss of the home?

As a side note, I am a bit concerned over their ideas only because the tech said 90 degree water will never heat a home, and while that may be true with a home with small conventional radiators, my home is sitting upon one MASSIVE radiator that is a concrete slab that is measured in cubic yards. I guess I am confused because it is hard to make an argument for something that is not ideally working.

You need to find new technicians. A condensing boiler will be most efficient with the lowest water temperatures.

You need to adjust the outdoor reset curve.

Im not an expert first off. I think you should start with temperature drop. The water coming back should be a certain amount cooler than when it leaves the boiler. Maybe its 30-40drop? 25 sounds more efficient. Compare the flow rate and the temperature drop and calculate BTU loss. That should tell you something. Once you figure your BTU use then you need to compare that to the fact that concrete floors can only give off 200-300 BTU per sqft.

I would start trying to figure out how to get the return water at the proper temp and go from there

Edit: it may be 20-30 BTU max out of 1sqft of concrete

Excellent advice so far, you need to tweak and play with your setting to learn your home. The techs only know what they learned in a classroom etc. I installed a tekmar injection system several years back and played with it for a couple of weeks to get what I wanted. It made an improperly installed pipe system work well, even in low temps with high winds. You know what is best, you know what it is telling you because you live there. read the instructions several times to fully understand what each control is doing and do it yourself.

Kevin

Techs pretty much hate getting called back for nuisance adjustments...they like the set it and forget it, see ya later deal.

Rob R. wrote:You need to find new technicians. A condensing boiler will be most efficient with the lowest water temperatures.

You need to adjust the outdoor reset curve.

Right but didn't I do just that by adjusting the Inside Start Temperature?

But you are indeed right regarding the technicians. It is so hard to get qualified techs out here...and you would not believe what I paid for them...slightly above a Benjamin per hour and they did little good. At the same time, I don't think they comprehend just what occurs to curing concrete when you start flooding high temp water through it. The term brittle comes to mind.

They did try and get my Munchin Boiler differential changed but could not do that either. Right now it maxes out at 140 degrees and kicks back in at 80 degrees, quite the difference to say the least. But that is only on the main loop, obviously the variable injection circulator mixes water from my returns so its not that drastic of a drop. There are adjustments for differential drop on the boiler, but they could not figure out how to do it so finally they gave up...kind of at my insistence because I was paying them well for very little help.

I was good about it and not upset, but I am frugal too. The only time they got testy was when he tossed out that in his 30 years of experience he never saw a boiler system that required two thermostats to call for heat in order to come on. Well this one does, I assume because the zones share the same monolithic concrete slab, and also efficiency.

BTW: If I come across as not sounding like I appreciate your help, I am sorry. I really do, I am just frustrated by my boiler continuously running and not getting my house warm enough. I can see when there are wide swings in temperatures as the slab has difficulty reacting quickly.

I might have to contact the guy that designed my boiler system and have him work on it. He is a nice guy but through divorces on both of our ends, it makes things a bit more difficult. (He is my former Brother-in-law).

You have a wonderful heating system - it just needs a little adjusting

it will heat the house when the outside temp is 40-ish with by circulating energy bearing liquid that may only be 80 degrees
but when the outdoor temp drops - the circulated liquid must be hotter

This is controlled by the degree curve the runs the injection pump - its a fancy way creating a temperature reducing loop

I have preached a lot about that and system balance, but I digress. Find the curve reset screw that drives that pump and set it just a bit tighter

Remember - and if you paid attention in my classes - you WANT the zone pump to run as much as possible and as long as possible and to do that you must make it sent out the right temperature to hold the load at human comfort

Kind Regards
Sting

NoSmoke wrote: So which theory is conserves the most propane: use high temp water controlled by thermostats and zone valves to heat the home but end up with wide temp swings, or

Use degree day theory to heat the home via varying the water temp flowing through the floor to account for heat loss of the home?

I don't know the answer to this but I do know which is easier to operate with a high degree of certainty and results in fewer "cold" complaints. I am in the oversize the boiler, simplify the system , let the peak efficiency pound sand school of thought. Too Ive sent more Munchkins to the scrapyard than any other brand , by far. Though Navien is catching up. For me, go cast iron with a standing pilot or go find another plumber. The gains to be had using these high tech systems is insignificant when compared to the costs of installing and maintaining them. Sorry for the no help critique but I feel it might help someone doing research to rethink the High tech route. If you feel this post should be deleted just say the word and it will be done.

waldo lemieux wrote:I don't know the answer to this but I do know which is easier to operate with a high degree of certainty and results in fewer "cold" complaints. I am in the oversize the boiler, simplify the system , let the peak efficiency pound sand school of thought. Too Ive sent more Munchkins to the scrapyard than any other brand , by far. Though Navien is catching up. For me, go cast iron with a standing pilot or go find another plumber. The gains to be had using these high tech systems is insignificant when compared to the costs of installing and maintaining them. Sorry for the no help critique but I feel it might help someone doing research to rethink the High tech route. If you feel this post should be deleted just say the word and it will be done.

No, I am not like that. Everyone has their own system and why they think it is best and they have a right to voice how they feel.

To me this is no different than work where the Navy allowed us a new type of welding process that was drastically different from what we were using. It was so different it as frustrating to figure out, but while some of us welders said we are not going to let this beat us and set out to figure it out, some welders decided to revert back to the old method. Both weld a ship together that meets the US Navy requirements. Which one is best? In a way the new style only because we have an extra "method" we can use that the older type of welders just don't have.

And so it is here. With the truth that no one knows my system as good as me, I set out to dial it in and got some amazing results. Not only is my boiler running a lot less, it seems to be more efficient at heating the entire home now then when it was running just half of it. I still think I can glean some more efficiency from it, but the comfort level is up with a lot less burned propane. That is always a good thing.

So what changes have you made? I'm really interested because I have a single loop of tube in half of my basement. The hitzer is in one half and thats plenty warm, there is a block wall running down the center of the house with one door and one window. The heat isnt equal throughout the basement but if I ever get around to putting a coil on the stove and running water through the slab I need to learn what I can from folks like you who have figured this stuff out in the real world. What temps are you seeing. 110 out and 80 in?

Update:

Really this is more of a thank you. With your suggestions I got a vote of confidence and started tweaking things on my own and adjusted setting over many days to let my concrete slab to adjust and wow, what a difference. With but a few minor changes in the Taco 705-2 controller and the house, boiler and system overall is running amazing well. I never thought it would be this possible to keep my house this warm, within 1-2 degrees in swings in a 24 hour period with so little consumption in propane.

I really have to thank you guys for your encouragement. Honestly it was telling me that "no one knew my system better than you" and it was honest wording. Thanks again. Amazing comport...amazing efficiency!!

NS
Glad to hear you turned the corner. Thanx for not taking offense to my reply as non was intended. What I should have said is that a system like yours is above my ability to install properly and understand fully enough to tweek just so. Kinda like a Dozer operator trying to be a brain surgeon Anyway good hustle and now you may be able to help someone else

waldo

Glad it worked out for you, I knew it would. I would kill for a properly install system at my house in Maine. I didn't say it before, but no, you will probably not heat your house with 90 degree water unless it is warm outside. And the wind is something the outside reset cannot factor. Enjoy that evenly warm floor!

Kevin

No,no, no...no offense at all, it is a very complex (and expensive system) and I have a difficult time finding people to work on it.

To me there is more than one way to skin a cat. Here in Maine a common one is for people to spend 12 grand on an outside wood boiler and heat their old farmhouse that way. It works, they burn a lot of cheap, green wood to make heat, but what if they took that 12 grand and fixed up their drafty house with insulation and new windows? Would they get a better return on investment? Same with a System 2000 or whatever, but you get the idea. Or what if they burned coal instead of wood?

I had a super tight house twenty years ago, but I think I need to improve upon that now. Maybe some better windows and stuff. I got an infrared camera so I am going to go about my house and systematically plug up the heat losses. As one guy told me, imagine your home flipped upside down and filled with water, with heat loss, where the water is coming out is where you want to stop up with insulation. Its really a good metaphor of what we should be doing.

At the rate we are building onto our home, I think if I keep going with the concept of keeping my house ultra-tight, then switch to heating via a coal boiler as the system and fuel; I think that will ultimately be the best answer for Katie and I. It still uses our high end system, it just uses coal to make it hot instead of propane.