Loading Valve over Thermic mixing valve

[huffdawg]

Giving the price of a loading valve. What are the advantages of a loading valve over a thermic mixing valve like a danfoss or caleffi ?

Huff

 

[BoiledOver]

Cannot comment on the loading unit. Am happy with the Danfoss after going up one step in temp to 158.

 

[warno]

I have the caleffi thermomix valve 1"and running 140 thermostat. It does it's job. Return temps never below 140 and if the whole system drops below 140 it shuts down the system side and just recirculates the boiler water. I'm liking it.

I also can't comment on the other option though.

 

[velvetfoot]

I'm totally unsure, but I think one thing might be that the loading unit allows natural circulation if power is lost.

 

[Bob Rohr]

In the case of the Caleffi 281 ThermoBloc, it serves as the system circulator, it may be enough pump to flow the boiler and heat emitters. It is a Wilo Star 16, which equates to 16' heat in Wilo speak, about 12 gpm is reasonable.

It is the return temperature protection, via the thermostatic cartridge and valve mechanism.

It also includes a "gravity gate" which allows gravity or thermosiphon circulation in the event of a power outage. With low pressure drop heat emitters like radiators, the is generally all you need for power outage overheat protection.

Think of it as a 3 in 1 device.

 

[woodsmaster]

I have a danfoss. one advantage to some people with a loading unit is it only takes one pass of the water to heat it to final temperature where with a thermostatic valve water may pass threw the boiler two or three times before reaching final temp. this is a non issue for me due to low heat emitters. I often only heat my water to 170 or so especially with the warm winter we are having.

 

[maple1]

I have a danfoss. one advantage to some people with a loading unit is it only takes one pass of the water to heat it to final temperature where with a thermostatic valve water may pass threw the boiler two or three times before reaching final temp. this is a non issue for me due to low heat emitters. I often only heat my water to 170 or so especially with the warm winter we are having.

I'm not so sure about that - would likely depend on the boiler. I have an LK810 loading unit, and I get 15-25° dT through the boiler depending how I load it & with what kind of wood, pump on speed 1. So it takes two passes to get my storage hot, if starting from depleted.

It works really well, is an easier & cleaner install, and allows for convection flow in an outage. But, it is more expensive, and after my sticking pump issue on startup this fall, I am not sure on the overall servicability of the pump unit. It is a Grundfos 15-58 3 speed pump body (painted gray instead of red), but I don't know if it can be swapped out for an ordinary 15-58 or not if you have bigger pump troubles & need a quick fix, or if it is an application-specific variant of a 15-58. I didn't investigate that - and likely would advise someone to check it out if considering buying one. At least with separate mixer & pump, you have things more modular & maybe easier to fix if something goes wrong - 15-58 pumps are everywhere, and if you keep a spare thermostatic element, you should be able to fix whatever needs fixing quick & easy with the valve. I would also like to know if any of the separate mixing valves allow for convection flow in a power outage. You might be able to get around that if needed & wanted by plumbing in a bypass line that bypasses pump & valve, that has a NO zone valve in it, maybe wired to the same circuit as a NO zone valve on a dump zone.

If anyone knows if an ordinary 15-58 pump body can be swapped into an LK810 in a hurry situation - I'm really curious.

 

[velvetfoot]

I would also like to know if any of the separate mixing valves allow for convection flow in a power outage.

I don't think that's the case for my Caleffi 280 ThermoMix.

All this doom and gloom failure mode talk and the fact that both of my boilers (pellet and oil) flow through that mixing makes me ask questions about these elements:
-How reliable are they?
-When they fail, how do they fail-closed (system doesn't work) or open (system not protected)?
-Does it pay to have a spare element on hand?
-Need a bypass be installed?

 

[maple1]

Sorry - didn't mean to sound so gloomy.

Merry Christmas!

 

[velvetfoot]

Right back at 'ya!
Now, on to supplyhouse.com for a spare element.

 

[Tennman]

Have Laddo and Caleffi loading units for feeding storage. Not much time on the Calleffi but both work beautifully and for me worth every penny. I'd buy Calleffi since Laddomat U.S. distribution is in flux at the moment. They do all the thinking for me. Both VERY quiet. I think by the time you buy all the pieces and plumbing, etc. the savings between the two approaches can't be much. I love them.

 

[DaveBP]

The ability of the loading units to thermosiphon water through the boiler during a power outage is dependent on a number of factors. It shouldn't be taken for granted.
And whether it can keep up with the heat output of an idling firebox might depend on how hot the water is coming into the boiler from storage ( and a bunch of other stuff).

Don't mean to discourage anyone interested in using one. I'm delighted with mine and wouldn't have it any other way.

I think part of the reason for their high price is simple elegance of design.

 

[Bob Rohr]

I'm not so sure about that - would likely depend on the boiler. I have an LK810 loading unit, and I get 15-25° dT through the boiler depending how I load it & with what kind of wood, pump on speed 1. So it takes two passes to get my storage hot, if starting from depleted.

It works really well, is an easier & cleaner install, and allows for convection flow in an outage. But, it is more expensive, and after my sticking pump issue on startup this fall, I am not sure on the overall servicability of the pump unit. It is a Grundfos 15-58 3 speed pump body (painted gray instead of red), but I don't know if it can be swapped out for an ordinary 15-58 or not if you have bigger pump troubles & need a quick fix, or if it is an application-specific variant of a 15-58. I didn't investigate that - and likely would advise someone to check it out if considering buying one. At least with separate mixer & pump, you have things more modular & maybe easier to fix if something goes wrong - 15-58 pumps are everywhere, and if you keep a spare thermostatic element, you should be able to fix whatever needs fixing quick & easy with the valve. I would also like to know if any of the separate mixing valves allow for convection flow in a power outage. You might be able to get around that if needed & wanted by plumbing in a bypass line that bypasses pump & valve, that has a NO zone valve in it, maybe wired to the same circuit as a NO zone valve on a dump zone.

If anyone knows if an ordinary 15-58 pump body can be swapped into an LK810 in a hurry situation - I'm really curious.

I have always been able to switch the motor and impeller by just removing the 4 allen bolts.

Generally any Euro based circ pump will have union connections. That type of pump is not so easy to find on the shelf at your supplier.

If the model numbers match I'll bet you could make the switch, after all the body of the pump rarely fails, it will be the motor or damaged (broken) impeller shaft.

 

[woodsmaster]

I'm not so sure about that - would likely depend on the boiler. I have an LK810 loading unit, and I get 15-25° dT through the boiler depending how I load it & with what kind of wood, pump on speed 1. So it takes two passes to get my storage hot, if starting from depleted.

My valve keeps return water at 140 or higher. I usually get a 20 - 30 F DT with 15-58 on speed one. My pump launch is set to 168 I believe, so one pass heats storage to around 170 or a little higher.

Edit : Oh, I see what your saying. I thought the loading valves adjusted pump speed.

 

[woodsmaster]

I guess some of my water is recirculating but it only makes one pass threw storage.