radiant heat modifications opinions

Alister

<span style="font-size:12pt">I’m looking into making some modifications to my staple up radiant heat system. Currently  I’m using  7/8 “ non barrier tubing, 3 zones, a triangle tube 110 boiler with an outdoor reset.  I have a 38k heat loss and a poorly insulated house.  I need to reroute some of the pex piping for some additional loops so I’m thinking about reducing the pex piping down to ½ inch as tubing funnels to the manifold to and from the manifold for easier flexibility.  I also believe I probably need to replace my cast iron zone pumps and am considering using zone valves and bronze pumps.  Feedback and opinions would be great.</span>

Jean-David Beyer

Consider better insulation.

I am not a professional, but it is my understanding that if your house is poorly insulated, the the most bang for the buck to improving heating efficiency is to insulate the house better (including fixing air  leaks).



Then, if you are using non-barrier tubing, and are considering replacing it with a different size, you should seriously consider using barrier tubing. The non-barrier tubing probably explains why you need to replace your cast iron pumps. I do not know which is cheaper, the bronze pumps, or the the barrier tubing. But your boiler probably does not like the dissolved oxygen in the water either, although with stainless heat exchanger, it may be OK. Why not a T.T. Solo 60, considering your heat load of 38K? You would get more use out of the modulating feature that way. It may not make sense to replace it though.



When I had my 55 year old boiler replaced, and converted it from one zone to two (actually three if you include the indirect hot water heater), my contractor recommended zoning with circulators instead of zone valves. It seemed a good idea at the time. The boiler is plumbed primary-secondary with only two zones in the secondary circuit. It seems to me that a delta-P circulator and zone valves would work as well, though I do not know the cost of the individual parts, other than the Taco 007-IFCs. Also, it may be more electrically efficient to use zone valves.

EricAune

Boiler/system protection

Have you considered installing a flat plat heat exchanger to isolate the boiler and cast iron pumps from the non-barrier tubing?  This will no doubt cost more upfront, but the benefits could save your boiler.  I know the TT well.  I know it has a great stainless exchanger and should be able to handle oxygenated water.  What I also know is what is going on inside the system, any ferrous components in contact with the water/fluid are corroding and creating a neat slime/sludge build-up that will settle into the exchanger and decrease it efficiency.



Bronze and stainless pumps are expensive, period.  Adding an exchanger will require an additional pump (bronze/stainless) but if your existing pump is salvageable and will be properly sized for the plate exchanger then you can still use it.



If you opt for just changing the pump then I would recommend a Taco 00 series, that way if it goes out then you will only have to replace the stater (cartridge) in the motor rather than the whole bronze/stainless pump.



If you are going with zone valves, I again would go with Taco and their EBV product.  Its an electronic ball valve (stainless ball, teflon seat and bronze housing) best suited for oxygenated systems in my opinion.  Consider a taco delta t pump with the zone valves, this will increase system performance and efficiency.