Is a hydronic radiant floor heating system dangerous for pianos to be sitting on?
Although its using the heating of water flowing through pipes, I can't imagine any evaporation is taking place, in which case, the floor can only be emitting a dry heat, right(?) - that can't be good.

newgeneration,

We have hydronic radiant floor heating in our entire house for 28 years now an for all the time we own a piano we never had any issue with the pianos even not with the tuning stability.

One should not forget that the water in the pipes is merely 30° C and that the whole system can heat your room because it acts as one big radiator with a surface equalling the floor surface of the room.

As a result there is much less air convection as with classical systems where the hot air migrates to the seiling of the room. During winter time it is no problme at all to keep room humidity within confortable ranges os 42 - 45%.
And as far as I understand there is no evaporation taking place with a radiator or airco system either unless there is a leak somewhere.

Some advice care if an upright is used in a room with hydronic radiant floor heating. The bottom of an upright is only some 10 cms from the floor and the way the case is conceived acts as some kind of a chimny (it sucks air from low to high); even with uprights I had no problems but e.g. Schimmel recommends some special floor protecting mat to be put under an upright. The soundboard of a grand is about 70 cms above the floor.

schwammerl.

Hey Schwammerl
Thanks for the personal experience! and also the mention specifically of an upright scenario. I should have mentioned that the piano to be considered is an upright where the case and soundboard/bridges are obviously close to the floor and even at 30 degrees C, that will definitely create a warmer heat that will be dry, on the lower portion of the piano.
Thanks again

There seems to be some fear and mystique surrounding radiant infloor heat regarding not only pianos, but woodwork in general. However the fear, at least in the US and probably in Canada was unjustifiably created by unfamiliarity with the system, rather not the physical conditions it creates. It is infact an extremely gentle consistent heat system.

In the 80's in the US, wood flooring manufacturers actively created and spread the rumor that radiant heat would destroy flooring by voiding their warranties if the flooring was used over radiant heat. The warranty voids were completely unfounded, and an retracted by most flooring manufacturers after a couple of years. The issue is and remains unfamiliarity.

In my own house we have radiant heat throughout the house, with wide (18"-20") pine upstairs and wide walnut(6-9") and bamboo (3-1/2") downstairs. I'm sitting on the pine right now, at the end of the heating season, 22 years after installation. Wood in the house is at about 6.5%mc, gaps in the boards are maybe 1/16", no cupping or extraordinary destruction(except from my kids...but thats a different story).

I was advised against installing the flooring over the radiant heat by the flooring supplier 22 yrs ago. However I know wood, and I knew he was spouting BS; I ignored him. THese floors are now routinely installed over radiant systems in high end construction because the heat is not an issue.

Same with a piano. The name of the game in piano health is temp and RH stability. Since Radiant heat is always on at a very low level, it produces consistent gentle temps which not only keeps the temp stable, but it can be keep the occupants comfortable at lower temps (this benefits RH levels).

RH consistency depends on the tightness of the building. Regardless of the type of heat used, a drafty building will create aggressive the rh swings. Any building that is excessively drafty will create RH conditions that challenge both human health and wood/piano health.

Frankly, the combination of a drafty building (ie aggressive rh swings)and forced hot air can destroy an piano in a couple of years. However forced hot air is never questioned as a heat source...why? I submit because forced hot air is familiar; radiant heat is not familiar.

Also keep in mind, Damp chaser systems work off of the radiant heat concept. DC rods are radiant heat sources right up close and personal to the soundboard, and they have proven their effectiveness in many locations and situations. They don't destroy the board, but rather they extend the life of the wood parts. This is achieved by creating a consistent temp./rh environment(or at least mitigating the swings).

Jim Ialeggio

newgeneration wrote "...The floor can only be emitting a dry heat, right(?) - that can't be good.>>>

Any heat lowers the RH of the area it heats. The equation is if you heat a given volume of air, the Rh of that same volume of air will drop.

So any heat will "dry" the air (read: lower the RH).

However, and this is a biggy, air movement aggressively accelerates the amount of moisture that that drier air will draw from the wooden objects (and people) in the room.

Of the various heat types, radiant heat alone creates no convection except secondary convection. All the other heat systems, forced hot air, baseboard, etc depend on convection, Therefore the removal of moisture from the objects in the room is accelerated by forced hot air and basebaord (not to mention wood stoves).

Combine that convection from forced hot air or baseboards with a leaky building and you have a death trap for a piano.

Radiant heat allows lower room temperatures (read higher RH), and very limited secondary convection.

If you are concerned about the bottom of the upright, a rug will very effectively insulate the bottom of the piano from these very gentle temps.

Jim Ialeggio

Very much appreciate your post Jim.
I trust very much what you have described but spare me one more query about the whole radiant floor heating......

The fact that when I put my hand on the floor, or feel from my feet that the floor is warmer than say putting my hand on the top of a table in that same room, wouldn't the bottom of an upright piano including the lowest portion of the soundboard feel/be warmer than something 'off the floor'? That warmth/heat that I feel, is that not 100% dry heat? I understand the convection concept of forced air and what you've shared of air flow and its effect on rh throughout the room, but therefore we make sure that pianos are not subject to the direct flow from a heating register.
A piano subject to forced air heating will experience some swings in humidity then (what you described and it makes sense to me) but the piano from top to bottom will remain temperature-stable. Whatever mechanisms are in place to address the rh in that room/home (humidity control attached to furnace or stand alone humidifier) will do the job of keeping the piano within an acceptable range. With radiant floor heating, will the bottom of my piano not be subjected to some drying moreso than the top? Heat rises but the fact is that the temp running under the floor is at least 10degrees higher than what is felt as the room temperature.

I just reread what I am writing and have a hard time figuring out what I am trying to express. Do you see what I'm trying to get at though?

John wrote..."I just reread what I am writing and have a hard time figuring out what I am trying to express. Do you see what I'm trying to get at though?"

Maybe...you seem to be concerned about creating a temp differential in the instrument.

Intuitively, that seems to make sense. But to play devil's advocate, where do we locate a DChaser rod in an upright? The fact that the DC rod is in one location sets up a similar temp differential, doesn't it?

I'm not sure how or whether this temp differential plays out in a significant way or not, however the easy fix to put your mind at ease is to set a rug under the instrument. Rugs on radiant heat are very effective insulators. This way the whole instrument will get the benefit of the even stable radiant temps, and the temp differential inside the instrument is taken out of the equation.

You mentioned "100% dry heat"...

This is an incorrect term, and what may be confusing you. Heat is heat is heat. It is not dry or wet. What creates the drying effect is the RH of the air that has been heated. The big difference between forced hot air and radiant heating is that in forced hot air, the air is warmed then that low RH is blown at velocity to warm the objects and people, and in radiant system, the objects are warmed, and then those objects (and people) gently warm the air.

In a radiant system the air is not heated. Repeat, the air, the "drying" component is not heated. Rather the objects, including the people are directly heated just like you are heated by the suns rays when you go outside on a sunny day. The objects warm the air. For this reason, significant air movement of low RH air, a major cause of excessive drying, does not occur in these systems.

Jim Ialeggio

THe old systems where terrible, too much heat, blood circulation problems, dust flying in the place. IO have seen numerous verticals that have suffered badly from those.
SO I haves some strong feeling about them.

Bu now I have seen some of the newest systems (some of them date from the 80 's)

The regulation indeed is important, as having a 30° temperature in a room is by evidence too much. The last systems I have seen where only gently warming but all year long, they work at night or early in the morning, to keep the room at constant heat of 19 ° 20 °c. In that case the piano is even having benefit of that.

But I have seen one of those superb systems installed in a piano teacher special teatching room. As he spend hours sitting at the piano he get cold and turn the heat knob.

Then the air get very dry (as in an owen, ) the feet feel the heat when standing at the same place, and the piano went out of tune badly, plus all the action screws unscrewn, that in a few weeks.

So ,a regulation and air moisture question, to me, more than anything.

I have seen a flat a few weeks ago with that system, and a wooden floor, : 30 years later the wood is not waving as I have seen in other places...

kamin wrote ...<30° temperature in a room is by evidence too much>

I'll say...30deg C is 86 deg f...that's down right dangerous to ones health, and frankly even nursing homes don't run temps that high.

<So ,a regulation and air moisture question, to me, more than anything.
Your post>

Exactly, as in any heating system. The bottom line is that heat, any heat lowers the RH of a given volume of air. High temp in any heat system will be detrimental to both wooden objects and human sinuses. Rather than looking at what type of heating system is being used, look at the level of heat, the draftiness of the space(drafts introduce huge amounts of cold very dry air to the space and cause you to turn up the temp...a major double whammy for aggressively drying the air.), and monitor the RH.

As a side note, there are a few MDs out there who have realized this connection between RH and temp, and are finally advising patients with respiratory issues to turn down the heat. A cheap an effective fix.