Browse Forums Heating, Cooling & Insulation 1 Jun 04, 2012 8:26 pm Hello there people, I have been renovating my house. I found out today that I have made a fairly large mistake, and I am hoping for some advice. I bought a hydronic heating system. It is wood stove with heater jacket, low pressure with mains coil tank and 6 radiators. Before I was ready to start installing it, I had to run some pipes for two of the radiators as the pipes had to go under the bathroom floor (I put in a new bathroom which has a raised floor of 180mm, and the pipes go under/through the screed I put in). I have now gone to have the hydronic heating installed and I have been told that the pipes I put through the screed are not rated hot enough for hydronic heating. The pipes are from Plumbers Supply Co-Op. It is part of theri PSC Pex Puch fit range. The product manual says the following about temperature rating: temperature ratings PE-X pipe is suitable for use at temperatures up to 100°C however; continuous long term operation should be between -50°C and +70°C under working pressure as detailed above. It is normal to have the stove circulating water to the tank via thermosiphoning, and this is supposed to continue even if the water in the pipes is boiling (don't worry - these pipes are copper). The tank has a little overflow/steam outlet pipe. So I guess the water in the tank will be just below 100C (really below 99C as I am about 300m in elevation here - yes I am desperate, every degree counts) sometimes, and there will not be much temp drop before it hits my regular hot/cold plastic pipe. I might also add, that apart from these pipes for the two radiators, all the other pipes I will do with the pink rehau pipe that is for hydronic, so the rest of the flow circuit will be fine. I have tried boiling a little section of the pipe, and it remains quite hard after sitting in boiling water for a few minutes. It seems to me that the pipes are fine for this type of temperature, but the manufacturer is just not willing to guarantee it. Perhaps it might fail about 10 or 20 years? I don't know. I have just moved into our new bedroom, for which the bathroom in question is an ensuite. I do not relish the thought of ripping out plaster, tiles, carpet, screed etc etc right now. It is realistically a few days work and at least $300 worth of materials to get the proper pipes in there. Has anyone used this type of black pipe for very hot water? If so, what was the result? Thanks Pip Re: Pex Pipes in Hydronic Heating System 2Jun 05, 2012 8:55 pm Why do you want to run your hydronic so hot? We typically run them much cooler than high 90's. Can you temper the water to within their spec range? @builderforlife Building inspector and passionate about construction When you need an expert to take a look. Re: Pex Pipes in Hydronic Heating System 3Jun 06, 2012 7:31 am The reason why I want to run it so hot is that when I build a fire in the stove, I dont want to have a shot off valve that restricts the temperature in the tank, as it reduces energy storage and costs money and time to implement. It was suggested to me last night by my dad to mix return water running off those to radiators with supply water to keep the temperature in a given range. I actually think that this is a brilliant solution, and I might think about doing it with all 6 radiators so they are not so hot that they will burn my children if they touch them. Is there standard off the shelf mixing device for this type of set up? Thanks Pip Re: Pex Pipes in Hydronic Heating System 4Aug 09, 2012 9:29 am Mixing valve is the standard with an uncontrolled heat source. Your tank is an uncontrolled heat source. However your pipe should be find as the working pressure of radiators is around 1.5bar, well under mains pressure of 7bar. 70 Degrees is more than enough to keep radiators warm. The Push Fit, is separate to the pex pipe as many fittings will work on the pex not sure about the push fits have used the shark bite push fits but they are expensive. Thanks Dave Does anyone have a suggestion for a good hydronic in slab heating speacialist who may be able to help me with an existing system and wether or not it may need a seperator… 0 4858 Currently renovating, and our main lounge is 5m x 10m, with a cathedral roof peaking at 6.5m high. Currently have tiles on concrete slab. Room is very hard to heat. I am… 0 4781 4 5099 |