Hello. I am new to this forum and have a question I'm hoping someone can help me with my question.
I just bought an upright piano. I have radiant heat from the tile floor slab
I have a humidifier nearby and can keep the RH in the low to mid 40 - 50 % range as measured on the top of the piano. The question is should I be concerned about the radiant floor underneath? I usually have the top of the piano slightly open plus there is the 1 inch gap underneath the keyboard so the ambient humidity should get in there I would think. I know there are damp chasers but I'm hoping I don't need to go that route. I don't have anything underneath the piano. The bottom of it is only about a quarter inch above the tile floor. Of course the radiant heat is not as intense as hot air or baseboard. Anyway, should I be concerned or am I probably good with my current set up.
Thanks ahead for any input anyone can offer.
Chris

Opinions vary on this. Much depends on the piano, your climate (how much heat is coming up form the floor, and for how long).

Not that long ago, many German piano manufacturers' piano warranty was voided if the piano was placed on radiant floor heating. I think things have changed now with different glues and manufacturing methods.

If you have an expensive piano, I would be wary. If the piano is new, I would run it by the dealer to make sure everyone is on the same page regarding floor heating and warranty. If you have a 90 year old upright, the continual low heat might slow cook the wood and the glue, causing permanent damage to the soundboard and structure.

No doubt others will hold differing views. Try doing a search in the archives, this topic has come up before.

I'm curious about this as well.

I went to tune a piano a few days ago, new customer, Yamaha C3. 25 cents flat on a heated tile floor. Supposedly tuned a year ago, but I don't who tuned it, or if it was tuned at pitch.

How would one protect the piano?

Dampp-Chaser with undercover

[quote=accordeur]I'm curious about this as well.

/quote]

The issues are, as with all pianos or wood structures:

-what is the ambient Rh (relative humidity)
-what is the rate of air exchange in the space (how drafty is the structure)
-what is the temp of the floor in relation to the ambient RH
-how stable is the ambient RH

These questions remain the same whether the heat is forced hot air, base board or radiant floor heat.

It is interesting that significant concerns and accusations have been leveled at radiant floors in relation to pianos over the years, all the while Damp Chasers, using a heat source which is indeed RADIANT HEAT, have empirically proven their effectiveness at protecting the wooden structure and pitch stability of thousands of pianos over a period of decades.

Put your hand under a Damp Chaser protected piano, and touch the wooden frame members...they are definitely warm to the touch most of the time, and the heater bars are downright hot a fair amount of the time.

The issue is not the type of heat, or even the actual temperature, but the Rh of the ambient air and the draftiness of the structure. The draftier the structure, in the winter, the dryer the structure's interior air will be, and the greater the swings will be in the equilibrium moisture content of all woods in that structure. Drafty buildings act similarly to a clothes dryer..they accelerate the rate at which moisture is taken from the inside of the building and dumped outside the building.

25 years ago, in my home, we installed radiant in-floor heat in a wooden plywood/2xjoist floor structure. We laid 20"wide pine floors upstairs, 5-8" walnut(which is not a terribly stable wood) and bamboo downstairs. Out of lack of familiarity, the manufacturers warned of grave consequences, and did not offer warranties.

I ignored their concerns, because I understood the principal involved.

The 20" pine is stable, flat. The seasonal gaps(which any wide flooring would exhibit) are very limited. In fact, the pine exhibits much less movement and gaping than any of the antique, drafty, 10% rh antique homes I've worked in over the years. Those antique homes, by the way are heated with anything but radiant heat. The walnut and bamboo are just peachy.

The wood, which is in direct contact with the heat, is stable, and the bamboo's laminations and glues, not to mention the laminated plywood that holds it all together, is fine. Why? My home is well insulated, with controlled air changes. Interior RH throughout the winter is in th 40% range...That's all...

I have one of my re-manufactured grands in this radiantly heated space. As I live in Massachusetts with its aggressively piano un-friendly climate, I use a full Damp Chaser system in the piano with a cover. I would do this whether I lived in a home heated with radiant floors or any other heat. The piano is stable and happy.

Jim Ialeggio

Thank you all for your input and/or suggestions on this. In answer to some of your question....s.
My piano is new and although not one of the more expensive high end units it is European made and has a great tone and it was pretty expensive to me. So my concerns are that I want to do the right thing and what's best for the piano. I did check the warranty and it doesn't specifically say anything about radiant floors but does say not to put it above any vents or next to a heat source. Kind of hard not to have it next to a heat source with a radiant floor.
I did ask the dealer and he didn't seem to think it was an issue and felt that as long as I controlled the ambient humidity around the piano I would be fine. But I'm a perfectionsist sometime and have read some things that make me wonder.
Since the bottom of the piano is so close to the floor and when the heat is on I am just wondering if the ambient RH around the piano is enough or not for the interior of piano when heat is rising from below. I suppose I could try and get a hygrometer reading from inside somehow to see what's going on. I also thought about using one of those emergency space blankets underneath since they actually reflect radiant heat. But it sounds like the RH is the deciding factor and not so much the actual heat from your viewpoint. That is good to hear.
I may end up getting a damp chaser anyway because my family often goes away and since I have no humidity system other than the portable room type I would need to have someone constantly fill the unit. It seems the damp chaser usually last a little longer between refills

Just to let you know I put an RH sensor inside the piano last night just to see if the RH inside was consistant with the ambient. It turned out it was only 1% difference which is very good. Unfortunately the heat doesn't come on much during the night as the floors are pretty warm through the daytime and we turn our thermostat down. We also have a ceiling fan nearby to circulate during the day time but that is off at night. So I probably should keep an eye on it during the day or when the heat actually comes on to see how consistant it is. If in fact it is really a RH and air exchange/draft issue and not a temperature concern perse then I think I can work that out I think. I still may end up getting the damp chaser just because I'm paranoid and also for when I'm away for a length of time and I can't monitor or maintain it. Also if I find out that when the heat is on it is very difficult to maintain that internal RH then I might just have too.

Thanks for the help. Chris

I am a bit suspicious of your humidity measurements. What were you using to take your measurements? The only hygrometers which will accurately measure differences of 1% are extremely expensive laboratory devices.

Jim, you touch on valuable experiences and factors.
As opposed to grands, uprights are sitting right on top of the heated floor, with a minimal air space below. That slow but continual heating of 10 - 15 degrees above ambient temperature over the months of a winter can really drive the humidity out of all wooden parts (essentially the whole piano). I would say it is akin to running a de-humidification rod inside a piano without humidistat control.

Can anyone explain how this could be a good or benign thing?

Jurgen,

I cannot vouch for the accuracy. It is a digital battery operated one
I got at Kmart however I did check it against the digital readout on my full house humidifier first and it was in the ballpark. This unit actually has two, one for indoor and outdoor. I put the outdoor one in the piano and the other on top of the piano. I should tell you I only had this piano a week so any long term effects wouldn't be evident yet. I share your concern as the bottom of the piano almost touches the floor.
I am going to try and test it more when the heat actually turns on a while and see what I get, as the first test that wasn't the case and there was only residual heat on the floor. Will let you know.


Thanks for the help, Chris

Jurgen,
A long time customer of mine with in floor heat called me a few years ago after he heard a loud noise coming from his piano. He removed the bottom panel and seen a crack above the bass bridge in the soundboard that had appeared. We decided to install a Dampp-Chaser system. Within a few weeks the crack had closed up and disappeared. Having that constant heat can cause problems with pianos.
I had installed a Dampp-Chaser system in a new Yamaha Grand last year. When I tuned the piano for the first time it was 3/4 semitone down in pitch thanks to the in-floor heat. I installed the system and return about a month and halve later to do a follow up tuning. At this time the piano was about 1/4 semitone sharp.
In- floor heat can cause damage to both uprights and grands

Wayne, I assume they had proper ambient humidity levels in the room and this happened anyway and this was true of other pianos being way out of tune due to radiant heat in this post. The more I hear and think of this the more I think I should go with the chaser. I do have a room with the radiant heat turned off and put it in that room but it is real small. Since I also live in an area with real high humidity in the summer I will have the reverse problem then and the chaser can address both.

Chris

Jurgen, I have these 2 comments re your question:

1-We have how many thousands upon thousands of instruments, grands and uprights in homes. Of those multitudes of instruments, a vast majority, if not all, will eventually exhibit some failure due to moisture cycling, some sooner rather than later. These vast majority of houshold pianos will all be in a space heated with some type of heat.

Now, someone comes upon one of those multitude of instruments, ie a tiny sample, in a home which has this unusual heating system. He sees it exhibiting the same degradation that appears in forced hot air, base board, and, God knows, wood stove heat. Interestingly however, in this special case (radiant heat) the heating system is called out as the culprit, whereas when the same degradation in noticed in forced hot air and baseboard systems, the degradation is simply ascribed to improper RH control.

2- Look at the constant level of heat right up at the soundboard in a Damp Chaser installation. Not only is the DC heater bar hot, but as a radiant heat source, it warms the wood, not the air (mainly)...man, its toasty in there. SO we have a RH control system that is proven effective over decades, achieving that protection by...applying a fair amount of continual heat to a piano. The difference between any heat and the DC heat, is that the DC uses the temp and water to create a stable micro-climate.

I submit, its not the presence of heat that does the damage, but the presence of heat, any heat, without appropriate moisture added to the air in a monitored and controlled fashion.

A further comment about this kind of heat..because of the nature of the heat (like DC heater bars), where, like the sun, it warms the objects first, then the objects warm the air, air movement, and thus clothes dryer phenomenon, is considerably less than in any convective heat system. There are fewer drafts caused by temp gradients.

Human sinuses are a very good barometer for RH at various temps. My experience when visiting homes with convective heat(ie overnight)is that my sinuses are considerably more challenged than when at home with the quiet non-drafty radiant environment.

Jim Ialeggio

I was able to check the RH and Temp. inside the piano through an evening and part of the next day so heat did go on. I was not able to see any difference between the ambient at the top of the piano and inside. In fact the temp was a little colder and RH a little higher inside than out. So at least for now it appears that the radiant is not causing any drastic issues assuming my RH/Temp gauge is somewhat accurate. It has been more on the mild side with the weather lately so the heater hasn't been on constantly or anything. I am also just testing it pretty high in the piano just above the hammers so I don't know whether lower or closer to the soundboard would be much different.

You can remove the knee board and put the hygrometer in the bottom of the piano to measure what's happening down there.

I do not understand why people would be concerned by radiant heat from below. In hot weather, rooms are heated by radiant heat from above. Pianos survive that all the time.

I will try that and see if there's much difference. Thx

I find that the floor heat is a big problem for uprights and the Damp Chaser does not solve it "all the way".
We have bought some thin plates with thinfoil on one side. They are made for isolating. So I cut them out and needled them unser some uprights with the thinfoil against the floor to reflect the heat from the floor back. It works quite well.