Using hydronic heating loop to brew

My wife and I are designing our next house, and we would like to put a hydronic heating system in rather than a forced air. For those not familiar, it uses loops of water lines installed in the floor of the entire house, filled with a water/glycol mix and heated by an on demand water system through heat exchangers. Each loop is independently controlled by a tstat and circulation pump. It is an extremely efficient way to heat a house in cooler climates.

Back to the point, most systems keep the temps coming out of the boiler at about 180°. I was wondering, could I use a dedicated loop controlled with a seperate controller to brew? I envision multiple small loops heated from the home loop through a heat exchanger and controlled by seperate valves. one in the hlt, one in the mlt, and one in the brew kettle. I could add an electric element to bring the kettle to boil. I could also add another heat exchanger and a cold water feed to cool the loop in the boil kettle and have an integrated immersion chiller.

Has anyone done or thought of something like this? It seems efficient to me in theory, using a very efficient boiler. And not that difficult seeing as the boiler would be existing, and adding one more loop at construction would be easy and cheap. Anyone have any input?

Is the pipe used for that system appropriate to use in contact with wort? Concrete is basic, but wort is acidic.

Doesnt matter what the pipe is. The loop I would use would be closed using whatever liquid inside and whatever material for the pipe (plastic, copper, ss). The heat is introduced into the loop through a heat exchanger from the boiler. I would probably end up using flexible copper pipe inside each kettle/tun and connected using pex (plastic).

I don't think the radiant floor heating system you described would operate at a temperature above 110 degrees. A baseboard heating system would operate at the temperature you mentioned.

I'm only guessing but, I think the integration and control of the heating system for such an extraordinary application would be more expensive than a dedicated system. I have no doubt that it could be done.

I think that you're going to find that it isn't worth it unless you really want to be able to say that you use your boiler for brewing. You'll probably only really be able to get things to 140 or 160 the engineering will be a nightmare, the boiler control will be complex, service technicians will throw their hands up. I'd install a whole house Krystal Klear water filter system and run an indirect fired hot water heater (storage tank with a heat exchanger) off the boiler this way you start with hot filtered water you can install a thermostatic mixing valve for all the other fixtures in the house and keep your indirect fired water heater really hot just for the brew sink.

I'm not too worried about the engineering/controls. I install the controls for work and would do it all myself. I'm just not as familiar with the ins and outs on the actual plumbing side, eg the rate of rise expected from a boiler set at 180. I just do 5 gallon batches, would it still not be worth it to even get everything to 140 or 150 then finish with electric? I'd rather not keep a holding tank at high temps. I'd think that would destroy any efficiencies gained by using a boiler.

I'm assuming that you will be running a high efficiency modulating condensing boiler with outdoor reset (this is really the best option by far for radiant heating and will save at least 30% in operating costs over a traditional boiler). There are two main challenges that you will come accross.

1) With the small load presented by your mash and boil kettle heating you are probably going to end up short cycling the boiler your entire brew day which is not good. Depending on the boiler there could be minimum off times or short cycling lockouts too. To prevent this you will need an engineer to design your heat exchangers and flow rates to ensure that you are pumping in enough BTUs. This will be especially true if you are using a unit that has a maximum firing rate of 100,000 btus or higher.

2) You will need to run your brewing setup off of the DHW controls (these are the controls built into most of these high efficiency boilers to run the DHW pump and increase the target temp to 180 instead of the lower outdoor reset temp) in the boiler to "trick" the boiler into producing hotter water than it wants to for heating the house. (Although if you went with a lochinvar knight boiler it does allow for the seperate house heating thermostats with different temperature targets and there are external controllers that can also do this)

The only way I'd use a heating boiler on an average batch size home brew scale would be to produce domestic hot water for brewing. If you install a high end whole house carbon water filter you can keep the indirect fired heater at a normal temp and have a real jump on heating vs dispensing cold through a point of use filter.

I'd love to see what you do with it if you decide to go this route and I'm sure that it is possible to do I just think that the added expense and potential hassle will make it not worth it.

Ah, I see what your saying. If I simply used a heat exchanger I would short cycle the boiler, thus your suggestion to use the dhw. Hmm, I will have to do some more thinking about it then. The way our plumbing contractors usually set everything up is to use a high temp loop and a low temp. The low temp is fed from the high temp using a variable mixing valve. I could take it off the high temp loop, but then I'd need another tank if I didn't want to maintain the actual dhw at high temps.

I will do some more planning and pricing on this. Thanks a ton for the input! If I end up doing this, I will definitely update!