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Joined on January 19, 2012

Last Post on April 24, 2014

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Less is more

@ March 17, 2014 6:23 PM in How would you do this?

I am looking at a similar job right now.
It has a little less heat loss but also has a hot tub heat exchanger that needs about 20k/btu.

I am thinking of using a Lochinvar WHN110 and the Lochinvar 3 temp mixing add on controller.

One mix temp will be high temp Hot water baseboard.
One mix temp will be low temp infloor heat
The third temp will be the hot tub which I think will run at about 140.
The DHW will be a priority indirect tank

One boiler, done deal.



@ March 16, 2014 8:31 PM in Boiler Was Plumbed Wrong...

If you answer the earlier questions you will get better advise.
I think the only reason the system worked before is that the boiler temp is turned down and the mixing valve is turned up.
Your drawing will not work very well.

Clean Work

@ March 16, 2014 9:33 AM in Boiler Was Plumbed Wrong...

That is a clean install.
You are correct that it leaves much to be desired in the design department.

The boiler pump is pumping directly into the expansion tank. It should be pumping away from the tank. This may or may not give you problems. the good news is that there is very little resistance in that loop, so the pressure differences are slight.

The closely spaced tee's going to the secondary are not so close. They should have 4x pipe diameter (max of 8x)  between them That would be 5" to 10" with 1 1/4" pipe. What you have might work, but again it is not quite right.

You are correct that the mixed loop will never work as drawn. It can't.

You are also correct that the boiler will not last long at those return temps.

I am guessing that your staple up install does not use aluminum plates. Is there a way to confirm this?

If your system is plateless, you could run the boiler and the staple up zones at 150 then mix down the slab zone with a device that will provide outdoor reset and boiler protection. The outdoor reset will help prevent indoor temp overshoots do to overheating your high mass slabs. You could use something like this and another circulator. You would also want to change how it ties into the system. you don't want the other heating circ pushing on it.

Normally, the circ that will not turn off would be wired into the green controller. I am guessing it is presently wired always on.

Do you know what the boiler aquastat is set to now?
What size is the boiler?
How big is the house?
What type of construction/insulation?



@ March 16, 2014 12:59 AM in smart 50 with tankless water heater

I though I recognized the dialect.
The plan looks pretty sound. The alpha needs to "pump away" from the expansion tank. I think I would just move the pump.
Where does the 009 go?

That works

@ March 15, 2014 2:58 PM in Confused about "pumping away" and Knight WH installation

I don't see a problem with what you are proposing.
Personally, I don't think lochinvar has spent time updating the drawing since they took on the firetube boiler. If it were me, I would put both circs as well as the expansion tank and fill valve on the supply side and call it a day.
I understand you wanting to pipe per manufactures spec.


@ March 15, 2014 11:41 AM in smart 50 with tankless water heater

First off, The outer jacket of the smart is steel. It needs to be in the closed heating loop.
Is the alpha you have stainless? It needs to be if you are using it on the domestic side.
The alpha is idea for zoned radiant loops, it is kind of a waste to use it on the domestic side where you just need a fixed speed.
I think what you are proposing will "work"  I don't diagree with you that it is "ghetto".
I have not done on of these. Folks that have seem to have trouble with the tankless controls and the delta t.
If you post a drawing you will get more feedback.


@ March 15, 2014 10:52 AM in Confused about "pumping away" and Knight WH installation

Wouldn't the system "see" either the bipass, a zone, or the the setup you describe as resistance? Wouldn't that resistance be far greater than the boilers resistance? I don't think the circulator will know the difference. The pressure will drop on the intake side regardless.
This post brings up some interesting points.

Respectfully disagree

@ March 15, 2014 1:15 AM in Confused about "pumping away" and Knight WH installation

If this was the kbn series, I would agree with the drawing and Gordy.
The wh series firetube boiler has the headloss of a bath tub.The circulator is essentially pumping directly into the expansion tank. The bipass valve or the zones would have far more resistance than the boiler.


@ March 14, 2014 7:05 PM in The Alpha, what is auto adapt

This post covered this pretty well


@ March 14, 2014 1:47 AM in Scott's radiant heating project

You can set any mod con boiler on the market today to whatever temperature you want. In order to achieve the efficiency they are designed for you need a low return water temp and an outdoor reset curve. I would size the radiators to 130 degrees max on the design day.
What happened to the modern hydronic heating book?
This is all in there.


@ March 13, 2014 9:26 PM in Scott's radiant heating project

You can run a  condensing boiler  as low a temp as you like.
130 or lower is good target on your design day. You will want to use outdoor reset as well.‎


@ March 12, 2014 11:33 PM in Radiant Floor addition to Steam system

If your boiler has enough capacity to do the job it was designed for plus the additional load you are proposing there is nothing wrong with your idea. You will have to add up the EDR of all you radiators an apply the correct "pick up factor" for the piping losses and check that number against the boiler output rating. If you steal too much heat, the boiler will not be able to produce enough steam to satisfy the radiators.

You are correct to use a  heat exchanger. The radiant loop should be a pressurize,closed loop.

You could heat your domestic water the same way. It needs to be another separate loop with it's own heat exchanger.

Both loops would be set up so that the boiler aquastat  would fire the boiler to a lower temperature setting when there is no demand for steam.

Don't be fooled into the common thinking that you are somehow getting "free heat" because the boiler is firing anyway. A boiler that large has a great deal of jacket, flue and piping heat loss. You will be running pretty inefficiently when just the smaller loads are calling.

Dan's books on steam heating are very informative. I would recommend reading all of them before undertaking this.

It would also be a good idea to post this in the "strictly steam" section. You want to get the attention of the true steam gurus (I am not one of them).



@ March 11, 2014 8:47 AM in What is this?

I think there is a very good chance that the radiators are serviceable. Leaking fittings are common and usually repairable. Do you have pictures of the leaks?
If the radiator is not getting hot, this points to poor distribution. The problem is more likely in the mechanical room not the radiator. As pointed out earlier air in the system is a likely culprit.
Pictures of the boiler piping would help. Does the boiler have a pressure gauge? What does it read.

You have won..

@ March 10, 2014 11:34 PM in Sizing a boiler in Watertown, MA

Congratulations, you have made it.
Insist on the correct size as you have calculated and enjoy a comfortable and affordable system.
You might want to remind the gentleman that is sizing for DHW that:
The 4500 watt electric heater he installed last week puts out 15,367 btu/hrs and the 40,000 btu 70% efficient gas heater he installed yesterday puts out 28,000 btu/hrs.
Enjoy your new found knowledge.

Check valves

@ March 10, 2014 10:19 PM in Flow check.

You only need checks at the circulators with that arrangement.


@ March 10, 2014 6:20 PM in Flow check.

If I understand your description correctly, that is all you need. Post a sketch if you want to be sure.

Check valves

@ March 10, 2014 2:57 PM in Flow check.

It sounds like the circulators need check valves.The zone valves will suffice for the zones. I don't know why you would add the zone checks.

How is it piped?

@ March 10, 2014 1:57 PM in Flow check.

Unless you have very large diameter pipes, I am not sure why you need any check valves. The zone valves will prevent flow when the zone is not calling. The main circ only needs a check if it is opposed by another circ.
How is it piped?


@ March 7, 2014 1:00 AM in Heat loss through rim joist

The rim joist area is a huge area of heat loss, particularly with radiant heat.
I think 3" of well sealed foam board of spray foam is a good idea.
What type of joists do you have?
You may be able to drill new holes and move the tubes over by creating an oval.
Yoou may need to reinforce the joists.

2 Way

@ March 6, 2014 8:48 AM in New Boiler Pipings

There is nothing in your piping arrangement to force the water to bipass the heat loop and recirculate through the boiler. As you have drawn it, some water will do this but you have no real control. For a simple setup you might want to look at a boiler protection valve


2 Way

@ March 6, 2014 12:39 AM in New Boiler Pipings

How are you addressing the condensation issue with a 2 way valve?


@ March 4, 2014 11:50 PM in New Boiler Pipings

Your new drawing is not addressing the condensation issue. You have to add a bipass of some sort. A 3 way or 4 way mixing valve with an electronic controller would be a good option.You could also integrate outdoor reset with this strategy.
Do you understand why the flow directions are incorrect in your drawing? It is not because you are calling one primary and one secondary.
The pipe flow rates and btus are listed in the conversion factors tab at the top of the website.
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