Laddomat vs Danfoss and Taco

[Tennman]

I've been to the Laddomat site and studied the Powerpoint. The Laddomat 21 is located exactly where my Danfoss is. I like the automation and mixing control it claims to provide. At the moment I've got my Danfoss so choked not sure how much mixing it's providing. Having mixing and charging done for me automatically is attractive. What I don't get from the schematic is how that pump at that location in the feed line to the boiler circulates water to charge storage. I can understand how a separate Taco turned on just in the storage loop works but I don't see how that Laddomat works even from the cool animation. Obviously it does tho. I'd really like to dump the Danfoss and use the Laddomat for our 60 Class system but not sure I get how it circulates to charge storage. I plan on keeping my Taco 0013 for barn to house circulation. Need to get a plan for boiler to storage control. Seems like several of us are planning storage addition at the moment. A hot topic.

 

[goosegunner]

Make sure the Laddomat can move enough water with the head loss you have in your system. They are designed to have very low boiler to storage head loss.

Danfoss makes a new valve that does close completely on the hot port when the desired return temps are reached. It only comes in 1 1/4".

gg

 

[jebatty]

Also look closely at the specs for the laddomat-type loading unit you may choose. One I have seen shows maximum flow at about 12 gpm. At delta-T=20, that is 120,000 btuH maximum, which likely is not enough to prevent idling for a 60 class boiler during high burn periods. It may be is satisfactory with greater delta-T and wood load burning down as delta-T closes to 20 and then less. 12 gpm may be satisfactory for a 40 class boiler. In all events, if the intent is to drive storage to 185-190F, hence very low delta-T, higher gpm may be needed and/or careful burns to make sure the wood load is well burned down (and boiler output is very low) if idling is to be prevented.

I have the Termovar and have no difficulty charging the entire 1000 gal of storage to 190F with no idling. All it takes is a little care in loading to make sure boiler output is falling as storage temp is rising.

An advantage of the loading unit is that is continues to cycle to extract maximum boiler residual heat to storage.

 

[Tennman]

Jim, I just re-watched the Laddo animation. I get now how it works. The thermal control valve first pulls from the boiler output line and redirects back to the boiler. As water heats up the bypass port is closed to pull more from the bottom of storage and chokes flow from the boiler output side until I guess all flow circulates between boiler and storage. Early morning is about the only time I have to mess with boiler stuff. My brain must have been clogged yesterday. I really like this approach vs me playing with a ball valve upstream of my Danfoss.

In the process of reading Laddo searches here I read someone discussing how the 21-60 was too small for a 60 class boiler. Per their website when I select the <80kW output I get the Laddo 21-100 or the 21 part number. As in about all my other calculations on my system, assuming 85% output efficiency tells me I'm outputting ~51kW on a good day. So I would have guessed their <60kW Laddo 21-60 would have been good. But you're correct, I sized my Taco 0013 to provide 12 gpm to get 180kBTU to the house. Makes sense I need the same flow rate to storage prevent idling. I'd love to hear from folks that have 60 Class boilers to find out what unit they are using. I read on one thread where Taxi was considering installing a Laddo. He's helped me a bunch tuning the Danfoss, but I'm tired of messing with it and looks like a Laddo provides the optimal control for me. All my boiler loop is 1 1/2" black iron, so I'd like the same fittings. Once I talk more with the U.S. distributor I'll post what I learn.

Also GG my storage will be close to the boiler in the boiler barn so head loss should be minimal. Unlike my round trip run between barn and house.

So, Jim, you like how this thing works for you?? I'm liking the operational functionality of this gadget.

Knock.... knock... any other Laddo users out there??

 

[goosegunner]

Talk to Brian at Upnorthenergy. He is the Effecta dealer on this site. I believe he uses the Laddomat with his designed installs.

gg

 

[taxidermist]

Larry,
Your storage will have to be close to your boiler to use a laddo As i think it only has a small pump . I looked into getting this one. http://www.woodboilers.com/uploads/public/TermovarLoadingUnit.pdf but with my storage in the house and the boiler in the barn it would not work.
Rob

 

[Tennman]

Yep, yer right. Gotta keep my 0013 to move all that water 400' round trip from storage to house. I unfortunately have no choice but put storage in barn with boiler. The laddo will be a few hundred more than just a taco but I won't miss the danfoss and the manual tweaking. Looks like a 21-100 will fit perfect. Now still gotta find a tank!

 

[Trex83]

Hello everyone,
we took a look also to those mixing valve assemblies before ordering. We already had the extra pumps, so we just ordered a Danfoss VTC with the 140 (60) thermostat. It opens at 100% (no hot water recirculation from the boiler) when it gets to 158(70).
We have a small pump that should give us easy 12 GPM (45 lpm) which should make sure there is enough flow through the boiler when its at 85% design output (50 kW for a BioMass 60). We are still worried that the pump may not have enough flow to transfer the heat from the boiler to the storage tanks when it is at peak output. I calculated a dT of 30 although its going to get tricky when the water in the storage is going to get warmer... The other option is to run the boiler at a higher temp, like 190 but put enough wood only to let the storage tanks get to 160 or 170. That way we'll always stay close to a dT of 20 or 30 and not let the boiler run amok when the tanks are near desired temp.

We also saw on the BioMass 60 sticky that some of you are using a throttling valve on the hot supply for the Danfoss VTC (circle on the valve diagram - return mounted p.3). Why then aren't using the mixing valve as it is? Is there too much by-pass of hot water through the mixing valve and not a lot of water from the storage tanks going to the boiler? It should close when it gets to 158 and only let water from the storage go through?
Thanks
trex

 

[maple1]

We also saw on the BioMass 60 sticky that some of you are using a throttling valve on the hot supply for the Danfoss VTC (circle on the valve diagram - return mounted p.3). Why then aren't using the mixing valve as it is? Is there too by-pass of hot water through the mixing valve and not a lot of water from the storage tanks going to the boiler. It should close when it gets to 158 and only let water from the storage go through?
Thanks
trex

I've had the same question, and keep seeing it pop up on here - and don't think I've ever seen a concise answer. The only thing I could think of was that the danfoss always lets some water through on the hot/bypass side no matter what the temperature is, and the throttling valve would limit that. But unless I missed it, I have not read it confirmed. Otherwise, I also see no need for a throttling valve.

 

[Trex83]

The only thing I could think of was that the danfoss always lets some water through on the hot/bypass side no matter what the temperature is.

By the spec sheet, there is a pressure difference of 4.35 psi between the hot and the cold lines (B - A). How it is interpreted, we don't know.
The only thing i can foresee is there will be recirculation of hot water until you reach 18over the setting of the thermostat. At that point, the resistance of the coil in the thermostat will block hot water recirculation and only colder water should come in the valve.
If the boiler pump relay turns on too quick and the water coming out of the boiler isn't over that max setpoint, there will be boiler hot water recirculation. Hopefully I can install a flowmeter and datalogger to measure whats going on. Still under setup right now.

 

[goosegunner]

The Danfoss VTC is a newer design that closes the hot port completely. Most here have the older style Danfoss that always allows some water through the H port.

With my older style Danfoss I have a ball valve almost closed to get the M port temp at 150. If I left it open it would short cycle the water and cause the boiler to hit set point.

The VTC would be a much better choice from my discussions with the Danfoss tech support.

The valve also allows service of valve if needed.

A circuit setter would be a better choice than a ball valve but they do cost considerably more.

gg

 

[taxidermist]

The Danfoss VTC is a newer design that closes the hot port completely. Most here have the older style Danfoss that always allows some water through the H port.

With my older style Danfoss I have a ball valve almost closed to get the M port temp at 150. If I left it open it would short cycle the water and cause the boiler to hit set point.

The VTC would be a much better choice from my discussions with the Danfoss tech support.

The valve also allows service of valve if needed.

A circuit setter would be a better choice than a ball valve but they do cost considerably more.

gg

So did tech support say we would no longer need a ball valve if we switched to the VTC?

I always open mine 3\4 until the temp of the boiler is climbing. By the time I put a full load in the burn chamber and the return temp is above 140* i shut the ball valve all the way. Sure would be nice if there was a hands free way to do it.

Rob

 

[goosegunner]

From what I understood when the return temp hits the temp of the thermostat in the VTC the hot port closes completely.

It has been a while but I think the valve is still recommended for initial control and also service.

I think it would be a nice upgrade from the older Danfoss. It is only available in 1-1/4". It does have a cv rating of 16 vs 20 of the 1-1/2" older style.



gg

 

[Trex83]

It is only available in 1-1/4".
gg

I ordered the 1" model for our system for the VTC.
trex

 

[Tennman]

Hey guys. Back from wonderful vacation up nawth where most of you guys live.... New England. Just wanted to thank all for the input and very interesting to learn Danfoss has created a bypass that operates how I first "assumed" it should work. Taxi taught me about choking the Danfoss with my throttling valve and voila.... more heat to house! Anywho, if I have time to add storage this summer I'm gonna go Laddo. Projects are stacking up and storage install may get overwhelmed. Hard to get excited about boiler work when it's 100F outside (like today here).

 

[JP11]

The way it was explained to me is that you are doing two things.

1... keeping the hot water touching the thermostat, a little flow, so the valve is never shut all the way.
2... you are evening out the head pressure between the tank and the shortcut around the boiler so that the two are equal and the water doesn't try to take the path of least resistance.

Don't know if that makes sense at all to you

JP

 

[Tennman]

Yep... it does. thanks.