Under floor heating pipes under rocket mass heater

Hello everyone,  i am looking to start constructing a stove in Our house. We have concrete floors but set in the concrete we have plastic under floor heating pipes. Will the temperatures caused by the rmh cause damage to the pipes in the concrete? I thought maybe to be sure i could build a 1ft foundation to insulate from the floor. The pipes shouldnt be hotter than 90c

If your stove has a lot of mass and it gets so hot it damages plastic in a slab under it then you  have other problems. The entire thing is dangerously hot. You should be fine as long as you don’t go overboard firing your mass heater. Use lots of mass and the heat should conduct in all directions and away from the the floor.

You don't want the mass heater giving a lot of heat to the slab directly under it anyway; all that would do is heat the earth which will not help the house. Rather than a foot of foundation, just lay a series of bricks spaced a brick or so apart, with air channels between them to allow free air movement. Then warm air can move out and help heat the room instead of the slab.

Glenn Herbert wrote:You don't want the mass heater giving a lot of heat to the slab directly under it anyway; all that would do is heat the earth which will not help the house. Rather than a foot of foundation, just lay a series of bricks spaced a brick or so apart, with air channels between them to allow free air movement. Then warm air can move out and help heat the room instead of the slab.

Hi Glenn thanks for the reply. I didnt really explain well enough. The slab sits on top of 30cm of styrofoam insulation and imbedded in it are under floor heating pipes which are designed for temperatures of up to 45c.

Your idea about the bricks spaced out under the Firebox is great. I would probably like to put a bigger slab of concrete on top of this in order to build the Firebox on something level.. Then space out the bricks underneath it to create the air gaps. Would standard bricks be ok for this purpose?

A very rudamentary diagram but id imagined something like this

Hi Robert;
Yes, regular clay bricks work perfectly.

In place of a slab, I suggest using a piece of cement board on top of those bricks.
A mix of perlite and clay contained by clay bricks will be enough to build your core on.
Much cheaper and easier than pouring concrete and will act as an insulator to keep your heat in the firebox.

Yes, a layer of cement board on the spaced-out bricks works fine.

The slab being insulated beneath does eliminate the waste issue, but exacerbates the overheating issue.