Radiant Loop off existing boiler?

Danscrew

My Friend asked me to look at his Boiler problem. He had a plumber tie in a radiant loop to his existing Boiler . The plumber installed a mixing valve ( cash Acme HX- 110) on the discharge header. ( 007 is piped pumping into boiler) 1 pump 2 zone valves located at discharge header for upstairs and first floor ) Cold side of mixing valve is piped to return suction side of pump. The tempered water from the mixing valve to the pex line with zone valve?
It should be in the supply line to mixing valve correct ?

The loop wasn't getting enough flow.
I told him the Radiant Loop needs a pump? 007 ? With a zone panel for control?
Now if I add a pump for the radiant loop do I need the zone valve on that loop or can I use a internal Flow check on the inside discharge of the 007 ? Looking for a Diagram and control diagram? thanks Dan

sonofaplumber

You need another pump yes. 007 is fine. Mixing valves are just like a tee. Can't expect the water to just go around there for no reason! No need for a zone valve once you've added a circulator.

I have basically this exact same setup for my kitchen. You shouldn't need a flow check, the mixing valve already has check valves in it and that's all you need. You typically don't see gravity flow in radiant systems where they are usually horizontal and have a big pressure drop.

A zone relay for the pump will control the flow and call for heat on the loop.

Here's a pic of what mine looks like. Very simple.

SWEI

007 might be fine -- or it might not. How many loops and what length are they?

Is this a high mass (poured in concrete) or low mass (heat transfer plates, Warmboard, etc.) zone? An ODR-controlled mixing valve (or an injection mixing pump setup) really works best for this.

hot_rod

The white pex loop that the mix valve and pump ties into needs to have a constant flow of heated water from the boiler. The 3 way thermostatic need a supply of hw and about a 20 degree delta T to function properly.
Does white pex that loop have a pump that runs when the new mixed loop calls?

Danscrew

The reason I ask about the zone valve is that the pex was hot 7 feet down the line. On the discharge line after the zone valve so I was getting some flow down the line. If I add a pump and I remove the zone valve I will still get some flow thru the pump? isn't it better to have a zone valve stop all flow ?
Another ? if I add a zone panel to a cold start boiler I need to add the TT wire form the zone panel to boiler to fire the boiler correct ? thanks Dan

hot_rod

A drawing of how this spaghetti is all tied together would help.

Is the radiant loop tied into a baseboard zone? if so that zone needs to be calling for the radiant tie in to work properly.

Harvey Ramer

Danscrew said:

My Friend asked me to look at his Boiler problem. He had a plumber tie in a radiant loop to his existing Boiler . The plumber installed a mixing valve ( cash Acme HX- 110) on the discharge header. ( 007 is piped pumping into boiler) 1 pump 2 zone valves located at discharge header for upstairs and first floor ) Cold side of mixing valve is piped to return suction side of pump. The tempered water from the mixing valve to the pex line with zone valve?
It should be in the supply line to mixing valve correct ?

The loop wasn't getting enough flow.
I told him the Radiant Loop needs a pump? 007 ? With a zone panel for control?
Now if I add a pump for the radiant loop do I need the zone valve on that loop or can I use a internal Flow check on the inside discharge of the 007 ? Looking for a Diagram and control diagram? thanks Dan

As you already know, the current setup has not a remote chance of working. The only mix valves that kind of worked in that configuration were those gaint Holby valves that cost over a grand.

Your pump absolutely must pump away from the mix port of the valve. Also important, you may not have an excessive pressure differential between the hot inlet and the cold inlet of the mix valve. In a nutshell, this means you will have to move your pumps to the supply of the boiler and build the mix valve off of the supply header, or change the piping to primary-secondary and build off the primary loop.

As far as pulling a radiant zone off of a high temp - low mass loop, the most successful way to do it is to allow the radiant to send the call for heat, run the radiant on an ODR mixing device and put TRV's on the high temp emitters. Sometimes it makes sense, most times it is best to go back to the source. Depends on boiler type, size and zone size.

Harvey

Danscrew

Hope this helps my friend wants to remove this boiler and install a new one next year.

So to get by till next year I would like to remove the zone valve

And pipe in a pump from the mixed side of the mx valve to the pump and reconnect the pex to the discharge of the pump ?

And temper it down to around 110 for the radiant it should work ? I will be mounting the pump and zone panel to the cement column in the pic.

The original way the boiler was installed is a bit screwy just trying to get by till new bioler is installed Thanks For all your Help Guys

hot_rod

Looks like that boiler has had a tough life! Why not do the upgrade now? It could use some serious help.
Do they have a CO detector in the room?

Danscrew

I said that to my friend time to upgrade he said its not in the budget I just need to know if what i laid out will work? thanks Dan and yes they have a CO detector in the Boiler room

hot_rod

I still do not see where that white pex loop connected into the boiler? A drawing would be easier, just sketch it on paper and take a pic with your phone and post it.

Here is an article that shows and explains the most common radiant add on methods with thermostatic valves.


http://www.pmmag.com/articles/84495-a-little-floor-warming-please-john-siegenthaler

sonofaplumber

@hot rod ,

I think you are asking about the picture I posted, which is not the OP's system, just an example for him to try and follow to see what needs to be done.

Yes the white pex loop has another circ (15-58) at the boiler.

Danscrew

Here is a sketch I just want to add a 007 to the radiant loop. To give it flow.
My friend wants to rip it all out next year and go new.
I need to know if what I want to do will work ?

hot_rod

It looks like the two existing zones have zone valves, correct? If so add a 3 rd zone valve and a loop like the middle pic.

So when the radiant calls, it opens that additional zone valve, that zv end switch turns on the radiant pump.

Really should have a boiler return protection valve if the radiant can lower the boiler return temperature for more than 10- 15 minutes. How large is the radiant area? Is it a concrete slab?

Danscrew

Hot Rod
Yes the existing 2 zones have zone valves.
I not a 100% sure on the wiring I will be using a taco zone panel to control
if it is a cold start boiler I need the TT on the panel to fire the boiler correct ?
And a jumper across zc and zr correct?
What's the best way to wire in the 4 wire Honeywell zone valve and the Circ Pump? off the zone panel?

And thank you and much appreciated for all your help
Dan

hot_rod

I can't speak for that Taco version.

With the Gen 2 Caleffi relay box with a call to zone 1, end switch on the board will close and #1 pump will enable, regardless if priority is selected or not.

If priority is selected, all other zones are held off until zone 1 satisfies.

By contractor request we added this feature, basically disconnecting the priority and allowing you to use it different ways. Priority, if chosen is always on zone one, regardless of which model you chose.

So basically a relay 1 has a pump output connected to it.

Gen 2 relays are just hitting the shelves

sonofaplumber

Just wire the end switch of the zone relay just like you would another zone valve. They all go in parallel to the aquastat. Boiler sees a call on the end switch, brings the system up to temp. Thermostat for radiant zone goes to zone relay, and pump leads.

You could even wire this for constant circulation if you wanted since this is temporary. then the zone would scavenge any heat left at the boiler at the end of a call. and your friend wouldn't have to buy a zone relay where he will probably need a multizone relay when he goes to do the replacement. As long as you don't end up with an overheat problem which you could counteract by lowering the supply temp at the mixing valve.

just wire the circ to l1, l2 to run constantly, wire the thermostat to the end switch with the zone valves.