Should I be worried about what I am observing and hearing (radiant heat install in process)?

RenovationWontEnd

I’m concerned with my radiant heat install in joist cavity for the 2nd floor. We have already installed pex in the concern slab for 1st floor.

My concerns:
1)When I asked for a heat loss calculation, he replied “im a contractor, I just install it”. He has a C20 contractors license. I thought that does include HVAC system design.

My remodeling floor plans state:
HVAC INSTALLER QUALS Installers must be trained in best practices.
HVAC DESIGN HVAC shall be designed to ACCA Manual J (Residential Load Calculation), D (Residential Duct Systems), and S (Residential Heating and Cooling Equipment Selection / ventilation / air distribution).

2)No specific layout plan of the pex runs and lengths up front.

3)didn’t install heat transfer plates because we have nails coming through subfloor and this could damage the pex. contractor said that for retrofits this is often the case, and for retrofits usually run pex along joist 1” from floor and insulate below to reflect the heat upwards.

4)pex seems to be run in a sloppy nature where some areas are touching nails or screws coming down through subfloor.

5)holes in joists are rough/have splinters that the pex is run through and i see some areas of damaged pex.

6)the heat temperature that will have to run to heat our upstairs (inefficiency)

hot_rod

that is commonly called the joist bay heating method. It depends on the conductive currents formed around the tube to heat the air space, which in turn heats the floor. It can work in low heat load situations. Generally considered floor warming, as per Uponor.

So you would really want to know what the heat load of every room is. To assure the system can provide that.

Some would suggest that method is good for 10- 15 btu/ sq ft. It will require a higher supply temperature, compared to transfer plates.

A typical transfer plate installation could supply 25 btu/ sq ft as a comparison, and it works with the more powerful heat transfer conduction.

I would stop everything until you see a room by room heat load.

Pex installed through holes can be noisy unless bushings are used and the tube can move around as it expands and contracts.

A product called UltraFin can help with performance of those bare tube systems.

IMG_0844.png

RenovationWontEnd

I will be calling all work to a stop until I see a room by room heat load and plan. I already see some scoring and chips on the pex (picture 1 and 2), I assume from the roughness of the holes. Should I also be concerned about this @hot_rod?

Someone on reddit, where I learned about this forum, also provided me with this info:

I'll summarize from the bible of radiant hydronic, (Link Below) Written by the guru John Siegenthaler, P.E.

10.13 Suspended Tube Systems

Rely on convection and radiation vs conduction to move heat from the tube to the bottom of the floor.

Reflective insulation below helps distribute heat evenly.

They operate at relatively high water temp compared to typical radiant hydronic (160 - 200 F )

Can be supplied by gas or oil boiler but beyond reach of a heat pump

An advantage is no need for a mixing device between boiler and distribution system

Very little thermal mass, it can heat up and cool down quickly.

with 2 1/2in tubes per cavity, an upward heat transfer of 20 BTU/hr with 180F water temp 70F room air temp has been suggested through modeling.

Tubing should be supported every 24 to 30 inches, and supports should allow for movement as the tubing expands and contracts.

should not be run near drainage traps, cold water pipes, or in contact w/ electrical wiring. all traps in a heated bay should be insulated to avoid water evaporation.

air sealing of the joist bays is critical to performance, including insulating and sealing the band joist, perimeter of floor, and any penetrations through the floor or joists.

hot_rod

maybe download the Uponor Design Guide it has all the steps to design the system from the load calc to the tube layout , flowrates, temperature tube spacing , etc

Suspended tube is usually spaced away from the floor to allow air currents around the tube. See attachments

The issue with reflective foil under old floors like that is it gets dusty and the reflective properties are all but gone. It needs to be and stay a shiny surface to have any value

IMG_9025.jpeg

Kaos

I don't see markings on the pipe are the oxygen barrier PEX? If they are barrier pex, rub a tube against the wood joist, if they squeak, they will make a lot of noise when runnig. For this type of setup you want oxygen barrier pex with an outside PE layer, ie non squeaky pex.

I would second the Ultrafin option for this type of retrofit. Works great and comes with all the bits and pieces to keep the pipes at the right location and away from nails. It also means much lower supply temperature which is good for efficiency. Plus you only need one pipe run per joist bay.

"air sealing of the joist bays is critical to performance" This should be highlighted. Air sealind doesn't mean stuff some batts at the end but either sealing with spray foam or with rigid foam board sealed in place with canned foam. Without proper air sealing , this type of setup will not provide much heat (been there, tried it, didn't work).

For insulation you want regular cheap batts. Shiny bubble wrap doesn't do anything, just looks good, it is really equivalent to R2 of insulation. I know it feels like it should but at temperatures here low enough that this "reflective" bit doesn't matter.

hot_rod

Here is what UltraFin looks like. The tube needs to be away from them joist and floor to work best. I've done it with two tubes in a bay, just stagger the UF as you go down the bay.

It basically amplifies the heat transfer from the tube to the space, enhances the convection.

But it is still critical to know the room loads. If you see rooms with 27- 30 btu/ sq. ft, then the radiant alone may not cut it on design or colder days.

Your system is more of a joist side heat transfer with tube stapled against the joist like that :(

I doubt you would see that 20 btu/sq. ft output.

Screenshot 2024-11-25 at 7.32.53 PM.png

epmiller

Without knowing exactly how much heat you will be needing above that floor I hesitate to make a blanket statement, but having retrofit my own old house and done some other design/install of floor radiant heat, this install is NOT going to work for anything beyond some minor floor warming. Even with a high water temperature and a correctly sized air cavity above the correctly installed insulation below, you will not be satisfied. Just for starters, the heat will not be evenly spaced on the floor and you will have warm and cold stripes.

Also, the higher the water temperature in the tubing, the more movement of the tubing which will mean noise as it slips back and forth through the holes in the joists and past those half-clip tube supports. Those are not the correct support for this type of installation.

This install is not even close to correct for Ultra-Fin either. I've installed that product too.

I don't know how the contract is drawn up, but stop this job immediately until you can be shown the design criteria for the job, how it is supposed to work and the operating parameters of the system. I don't know everything about floor heating but I know enough that this install at best will not work well and maybe even not at all.

Ironman

All nails and protutions should have been ground off and heat transfer plates used.

It really makes no sense to use a mod/con boiler and then run a 180*+ supply water temp constantly. With good plates, you could get 20 btus per square foot with 120* SWT and the boiler would be operating above 95% efficiency. With 180* SWT, you’ll be at 86% or less and will require high temperature venting materials, like PPL, since the flue gas temperatures will be constantly above the 149* limit of PVC.

Judging from the old sub flooring of your house, it’s probably gonna take more than 20 btus per square foot to heat it in cold weather.

That brings up another matter in addition to the load calc: the R value of the floor. The thicker the floor, the higher its resistance to transfer heat. If you get above an R2 value, it’s hard to get enough heat transfer even from a well designed floor. The actual R value in each room needs to determined and compared to the heat loss and capability of the floor.

I’m not impressed by your contractor.

hot_rod

I have seen floors running that hot start to smell. In one case the asphalt impregnated paper used under the old narrow strip hardwood started to emit an oil smell as it got hot. It was a direct staple up, similar to what you have but attached to the floor.

RenovationWontEnd

thank you everyone. i have put the breaks on the current work. i think i will be able to get the contractor to install ultrafin. i'm still digesting the info i've learned here. there is a big language barrier between my contractor and myself. he did put me in touch with his distributor contact, and this contact seems willing to work with me to get the implementation corrected. i may try to do the heat calculation load myself.

EdTheHeaterMan

One of the things that I remember from selling PEX for radiant floor heat was in a seminar that I attended by Wirsbo who conducted it about 30 years ago. When you are using suspended tubing in the floor joist the way that you have it, or the way that UltraFin is designed, you are creating a heated plenum using the floor, the Joist and the insulation below the tubing. What many installers forget about is the end caps of the joist space. At each end of the joist bay there is a 14"x 8 to 10" box plate on the exterior wall and there is a 14" x 8 to 10" opening at the center support that is often forgotten about.

If those ends are not sealed properly, air can enter at one end and exit at the other end, as a result of the higher temperature in the joist bay. This will create a convection current that will remove the heat from the floor and end up out into the walls or outside, thru wiring holes and unsealed seems. Before you place the bottom insulation in the joist bay below the tubing, you MUST caulk all the wire openings, all the corner seams, all the end caps at the box plates and place insulation at those exterior box plates in order to seal the plenum tight like a refrigerator door gasket. Then you install the bottom insulation. Then you caulk the bottom insulation to the floor joist.

Can you count on your contractor doing that? You want to see how that floor joist cavity is sealed before you let them put the bottom insulation in place. Once that is done you will not be able to see the cut corners that might happen.

HomerJSmith

I never do under floor without Heat Transfer Plates (HTP). Heat Transfer Plates will lower the delta T over the staple up that your pics show, that is because the Plates will suck BTUs from the tube more than the tubes are able to ex-spell on their own. The maximum tubes with HTP in a 16 O/C bay is two. The amount of BTUs that radiates into the room is dependent upon the floor covering, Backloss, Supply Water Temperature (SWT), and the temperature delta T. It is always better, I think, is to over size the heat emitters for a given loop than not, because it would allow you to go to a lower SWT to maintain a comfortable room temperature.

Also, HTP minimize banding. Backloss must be minimized with insulation. Your present situation makes it difficult to put insulation under the floor in the joist bay and have heat transfer. With HTP, you can insulate up against them and not impede the heat transfer thru the floor.

I like solid 4' HTP and I put corn starch on the groove so the tube slips easily in the groove as the tube expands (ticking). I use to use talc but that's banned because of cancer concerns.

Jamie Hall

Not goint to comment on the heating, but… there is one picture which shows 8 closely space holes drilled holes with about 4 feet of the end of a joist. That joist no longer has any real safe load capacity, and will take a rather fancy sister UNDER it to restore strength…

hot_rod

it’s an ugly job, lots of sparks, but I have cut nails off with a die grinder with the guard removed. Disclaimer*Not the suggested way to use a cut off wheel.

To Jamie’s point, google joist hole drill charts to see what is acceptable for hole size and spacing. Usually an 1-1/2” hole can be drilled anywhere in a joist, but maybe not a series of them?

IMG_0849.jpeg

IMG_0848.png

IMG_0847.png

RenovationWontEnd

Yes, those holes are also very scary. I will be having another structural framing inspection scheduled and make sure I am present during that. One question @Jamie Hall regarding your comment "with about 4 feet of the end of joist"…that is where the center wall of the house is. it is not on either of the exterior sides of the house. is that still considered end of the joist? the joists run from one exterior side to the other exterior side. does that change your opinion. i'm going to take some pictures with a measuring tape of that (for my records) and will post here when I do.

RenovationWontEnd

Can i safely use those Heat Transfer Plates (HTP) @HomerJSmith if we grind off any nails protruding from above subfloor? Do you use them in those situations? Do I need to be worries above nails poking through into the pex even if we grind down the protruding nails due to the floor expanding and contracting?

RenovationWontEnd

I have been researching the joist holes last few days. I can't find anything definitive about joist holes. https://www.eng-tips.com/threads/multiple-holes-in-floor-joist.514490/

hot_rod

IMG_0849.jpeg

hot_rod

I would highly recommend the aluminum extruded plates. They provide a solid grip on the tube to avoid the squeaking of the tube moving in thin aluminum plates.

Thin plates can also make an “oil can” pop sound as they expand and contract.

Most of the radiant tube manufacturers offer the extruded plates.

But, the load calc will answer all the questions on what installation method is best for your application. There are a number of load calc programs online. A free demo at www.hydronicpros.com of the load calc I use. If you want to try one yourself.

https://radiantdesignandsupply.com/new-page

RenovationWontEnd

I meant to say I can't find anything definitive about the #number# of joist holes.

Kaos

Any number of holes as long as they are near the center and spacing between them is met as per Hotrod's earlier picture. LVLs are a different story, so if they ran pipes through a beam, that can sometimes be problematic.

From your pictures, I don't see an issue with the drilling of the joists but always good to get a professional to check it.

Grinding nails is ugly work and never perfect. This is my earlier recommendation of the Ultrafin install, simpler and it also keeps the tubes away from future errant nails.

About the only thing you need to do is a bit of air sealing around exterior rim joists, not a big job. A couple of sheets of 1.5" rigid insulation, cut it into squares about 1/4" smaller than the joist end space, foam it in place with canned foam. You don't need to air seal around the interior. If you are using faced batts for bellow the joists (easiest to use), staple the batt and facer to the subfloor near the interior walls. This somewhat closes the end off and limits airflow.

Your dual pipe install can still be used with ultra fins. What I have done before is split the UF pair and put one half on each pipe with the fin pointing towards the center. You'll need more turn keys to do this.

Make sure to confirm that the existing pipe is oxygen barrier pex. If not, remove and start from scratch.

Jamie Hall

Hmm… well, the saving grace is that it looks like older (possibly pre-WWII) timber, which is a lot stronger particularly in shear than the modern stuff. Further, the support for the joist is on the bottom — it's not notched at the end — and it is a multiple member application. I still don't like it, and I wouldn't put a piano on the floor above it, but… there were better ways to do that.

RenovationWontEnd

I've confirmed that the pex does have oxygen barrier (https://mrpexsystems.com/online-catalog/radiant-mrpex-pex-a-tubing-w-oxygen-barrier/ 180 max temp); still concerned with the damage I see on some areas of the pex.

Kaos

If it is this then you are good. That is also non-squeaky pex.

https://mrpexsystems.com/wp-content/uploads/2018/11/Submittal-MrPEX-PEX-A-with-Barrier.pdf

Hard to tell from the picture how much of the pipe got shaved off, hydronic heating is pretty low pressure, so not much stress on the tubing.

JMWHVAC

I hate to see shavings coming off the tubing, but to be fair, it happens. I literally take my knife and remove the sharp edges of the hole before pulling it in, but I am paranoid. Those scrapes (unless really severe) will not compromise the strength of the pipe but it is removing a bit of O2 barrier. After system has been in operation for a while it makes dark spots on the tubing evey place the O2 is getting in. The damage to the O2 barrier during install is one reason pex systems still get more O2 into the system than good old copper/steel systems.

As someone who has done floor heat for years, I still do staple up on a typical room on almost all jobs. The bath on the outside corner or the sunroom will get plates. On a typical job I am happy if my design temp is 140* and some jobs it is a good bit higher. You may say 110 would be much better and more efficient! Sure. But seriously, the $1000s that joist trak will cost to add to a whole house will not be recouped in savings for …. what… decades??? If doing plates on a floor with nails, use the extruded style because the tubing snaps in the underside of plate thus the tubing won't be pushed against the old nails.

As others have posted, you must know what all layers the floor consists of. If you take a shot in the dark, expect to miss sooner or later.

Mad Dog_2

May I ask How you came to pick this guy? Mad Dog

HomerJSmith

If you use HTP , you must grind off any protruding nails thru the subfloor. I use the following grinder and wear eye protection when grinding. You can buy this grinder for peanuts at Harbor Freight stores. Cheaper than a pack of cigarettes in New York city.

https://www.harborfreight.com/5-amp-4-12-in-slide-switch-angle-grinder-58092.html

Ironman

Here’s the plates that we prefer. 6 screws hold one plate which holds both pipes in a 16” OC joist bay. Single tube plates can be used in small narrow bays.

RenovationWontEnd

I tried to use the free demo of Heat Load Pro at https://www.hydronicpros.com/ but no windows computers in our household.

Kaos

This is a pretty accurate on-line tool (need to register but free):

https://hvac.betterbuiltnw.com/Account/Login.aspx?ReturnUrl=%2F

The hard part with existing houses is how leaky the place is, there is no easy way to get an accurate handle on this except for a blower door test. Older houses definitely tend to be on the leaky side.

RenovationWontEnd

I have replaced all windows and reinsulated most of the house in the house in last 8 years so hopefully that will help me use the tool tom come up with estimation. thanks for the suggestion (on thanksgiving none the less)

GW

https://forum.heatinghelp.com/discussion/comment/1823032#Comment_1823032

That's like asking your buddy how he came to pick his x wife—-you may not get an answer on that one 😀

GW

My house has gone through two generations of radiant—20 years ago was staple up. 12 years ago was the sandwich. Anyway, when you grind, you'll get some smoke in the home (burning some wood) and you'll have burn marks everywhere. You really want the nails inside the wood, or at least flush. It's not a fun job but if you just put your nose to the ground, it goes pretty quickly.

RenovationWontEnd

I hired the company for radiant that my GC recommended. GC was recommended by our structural engineer. I had received a quote from one other radiant company prior to hiring our GC. The company we hired does do radiant in this area, has several active radiant jobs (when checking city permit records). At the time, I felt that it was best to hire people that has worked with each other in the past and had developed a working relationship.

RenovationWontEnd

I've used the HVAC Sizing Tool to calculate the heat load/loss. I have not yet updated the actual ufactors of the finished flooring. Heated slab on 1st floor will be porcelain tile, 2nd floor (underfloor subfloor system) has engineered wood in front and porcelain tile in back. I need to figure out how best to enter these differences. Also, curious if I should try adding a heating type to the data I've added. I don't see "boiler" / "combi-boiler" / radiant heat as option. only gas/electric furnace, electric zonal, heat pump central, heat pump ductless. I am using the "non pro" mode of the sizing tool currently; maybe the pro mode has options that would help me.

hot_rod

this is a more hydronic friendly, simple program. See if it still loads as SlantFin closed shop.

https://slantfin.com/slantfin-heat-loss-calculator/

hot_rod

Or if you still own a pencil and eraser, here is another free download

All of these various load calculators are based on the Manual J from ACCA, so results should be similar

IMG_0855.jpeg

Kaos

https://forum.heatinghelp.com/discussion/comment/1823520#Comment_1823520

Heat loss has nothing to do with your heat supply. Once you have your room by room numbers you can figure out how to supply heat to that space. That is when the R value of the subfloor and covering come into play.

Overall, in cold climate, I would not recommend much tiled living space, it will be too cold in the shoulder season to be comfortable under bare feet unless you do careful layout to only heat where you are walking. This is possible but does take proper design.

For example, even my kitchen has hardwood and I would not change it for tile. Bonus with wood floors, if you accidently drop plates or glasses and lot of times they don't break.

RenovationWontEnd

Looks like slantfin no longer available. Maybe I'll try playing around with the spreadsheet a bit.

I'm in the "Mediterranean climate" of northern California so it doesn't get cold (compared to Syracuse NY where I am originally from).

Attaching screenshots from my heat loss using the HVAC Sizing Tool. I'm not sure if my 1st floor (that has slab) is accounted for since I didn't mark any of my rooms as "in basement". I included garage and laundry room in "conditioned space" though they don't have heat but are insulated.

Kaos

A bit on the high side for the warmer climate based on the envelope description but probably in the ballpark.

So most of your rooms are 10BTU/sqft, there are some a bit higher with the big room at 20.

The existing staple up will work no problem up to 10BTU/sqft. For the higher loss ones, I would go with either heat plates or ultra fin. Size the spacing of the heat plates to supply the /sqft load in those rooms.

It might also be a good idea to extra heat to the tiled spaces and have the balancing set for those to supply the bulk of the space heat. For example during the shoulder season the floor heat in my bathroom will supply enough heat without needing to run any other zones and keeps the tiles there nice and toasty.

Something to keep in mind that at 10BTU/sqft your floors will not feel warm even on the coldest day. They won't be cold and the house will be comfortable just don't expect toasty toes feeling. It is not real winter here yet, 25F outside, and my floors are at 75F.

RenovationWontEnd

How did you arrive at the below conclusion based on the heat loss info I provided?:

"So most of your rooms are 10BTU/sqft, there are some a bit higher with the big room at 20"

I thought that my next step is to consider the R-value of the subfloor and covering to get to the heat supply necessary based on the below comment:

"Heat loss has nothing to do with your heat supply. Once you have your room by room numbers you can figure out how to supply heat to that space. That is when the R value of the subfloor and covering come into play."

Apologies for all the questions, and appreciate all the help and support from you and this community forum!