Tekmar 256-2 and old American Standard boiler.

Mark J Strawcutter

Older cast iron boilers like yours seem to be able to stand up to low return temp and resulting condensation quite well. My system is so over-boilered and over-radiated that it ran for 30 years at temps rarely over 120degF.

The tekmar units are nice, but there are lots of simple "reset only" controls out there that aren't as expensive.

An "in-between" unit to look at is the Honeywell AQ475

Mark

Rob T

First off I want to

thank everyone who has helped me in the last few weeks with my heating system rebuild.

With this sites help and Dan's books I have completely re-piped my boiler(It is now pumping away with an air eliminator and bladder tank), added 3 zones, a LWCO and a new aquastat control.

Now on to my next quest...

Having read this post:
http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=9921&mc=20

I am thinking that maybe an outside reset would also be a good thing.

My #1 question is: Will this control co-exist with the new Aquastat (Honeywell 8148E) or does it replace it?

From what I can see the Tekmar would work in conjunction with the Aquastat, is this correct? I am hoping so as I just got the new 8148 installed and wired.

My 2nd question is: Is this a fairly straight forward install? I had no problems wiring the zone valves and Aquastat, is this along the same lines as far as complexity?

3rd question: How do I determine what would be a safe return temp for my boiler? It is a mid 60s American Standard atmospheric 165kbtu hot water setup. Quite massive and works fine (Of course it now looks like it is extremely oversized for my house) and I really don't want to replace it for a couple of years.

4th question: My B&G series 100 pump is making some noise in the bearings and I was wondering if it would be better to replace or rebuild it. If I replace it what should I use?

Thanks!

Rob

jeff_13

tekmar are easy for the pump try some mobli one oil in it it real helps my motor rebuild shop swears by it and i use it all the time i have free up motors that were tight now free also noisey now quite good luck

jeff_13

tekmar are easy for the pump try some mobli one oil in it it real helps my motor rebuild shop swears by it and i use it all the time i have free up motors that were tight now free also noisey now quite good luck

HP80

This is only my opinion and I am sure most of the true Boiler People here will disagree with my selection of controls (but I am only a controls person)? Tekmar does make a great control for boiler application. I prefer to use the Johnson Controls System 350 indoor outdoor controller. But firstly you must understand that the Honeywell L8148E controller is just a limit controller that provides high limit (temperature) protection and switching for burner and circ pump as well as in your case the "E" version provides zone protection. This said you have bought insurance but now you need to determine what kind of governor you will put on your newly purchased engine ( high and low Temperatures and set back). The System 350 from Johnson Controls is a modular (or lego type) system. This means if you add or loose a zone you add or loose a module from the control package. This is great beacuse if you have a problem zone you only pay for the replacement of that zones module not the whole control.
I am sorry I am starting to ramble but if you would like me to continue please email me and I will be glad to help you with the controls side of your system!

Rob T

Thanks for

the reply. I really appreciate it!

From what I can get off the net the 350 looks to be overkill for what I have.

All I am looking for really, is a way to modulate the water temp as I already have all the zones hooked up and working.

The way it is setup now is with 4 Honeywell 8043F zone valves powered off their own transformer. I am using the end switch to trigger the L8148E which, in turn, (As you stated) triggers the gas valve (If the high limit is not tripped) and kicks in the circulating pump. The circ pump also has a low limit switch between it and the L8148E which is set at 130F. There is also a LWCO between the L8148E and the gas valve.

With this setup how would the 350 integrate and would it supercede the L8148E or just work with it?

hydronicsmike

G'morning.

If you want to use tekmar, I would recommend a 260. It will give you Outdoor Reset and Boiler Pump Control to gain Warm Weather Shut Down, Purging and Excercising. Your Aquastat would become another limit device, where the tekmar (or any Control you'll use) will be the 'new' Operater. Your Zone Valve Motor End Switches would enable the 260.

The 256 doesn't have a Pump contact and you wouldn't want the Pump operated by the boiler in this case. You would have to add another external Relay, so that the Pump comes on when ever the Zone Valve Motor End Switch makes to ensure flow past the controls sensor. Without it, the Pump would only run while the Boiler is firing and in many cases the Control may be satisfied with the temperature, but the zones still need to get it. I hope this makes sense.

Regards,

Mike

Rob T

Hi Mike,

Thanks for the info, it makes sense to me. Guess I should have done some more investigation before jumping in with both feet and adding the L8148 to my system.

Looking at the schematics on the 260 it looks like it will control pretty much everything on my system.

If I were to use the 256 wouldn't be possible to still utilize the 8148 as a pump control? Or is this going to be a wiring nightmare that wouldn't work anyway?

Thanks again, I am learning daily here..

Rob

Rob T

Thanks Jeff

I'll try the Mobile One.

Rob

hydronicsmike

Your Pump

would have to be on an external Relay, like shown in A256-2. By the time you bought the 256, the Relay and your time wiring, you could have gone with the 260 to begin with. Plus you are not getting features that the 260 would have.

Hope this helps.

Mike

Rob T

I guess I will

forgo the outside reset at this time. Wouldn't mind having it but since I just added the 8148 and this would supercede it I can't quite justify the costs involved.

Goes to show you really need to do your homework before jumping in..


Thanks again Mike!

Rob T

That's what

I was looking for. From what I can see I can use the AQ475 and still retain some use of my L8148.

Checking out the schematics supplied by Honeywell they have one setup wired just as I imagined it could be done. They use the boiler output of an R8889 to trigger the AQ475. They use the 475 to run the pump and the R8889 to run multiple zone valves.

From this I figure I can use the boiler output on the 8148 as a trigger in the same way. I can then either leave the circ pump on the 8148 or move it to the 475. Either way the pump will only run when there is a call for heat.

Thanks Mark!

Mark J Strawcutter

dry vs wet contacts

I don't think you can do what you're proposing.

"dry" contacts - a switch
"wet" contacts - supplies voltage, connect to switch

The "burner control" contacts on the 8889 are dry. The "thermostat" contacts on the 475 are wet. The "boiler aquastat" contacts on the 475 are dry.

You don't want to hook wet to wet or dry to dry.

Wire up the end switches in parallel to the thermostat contacts on the 475, the boiler aquastat contacts on the 475 to the thermostat contacts on your 8148. Move the circ over to the 475.

Mark

Mark J Strawcutter

8148 not wasted

since the next logical step is to re-pipe to primary/secondary with the 8148 controlling the boiler loop circulator and the 475 controlling the system loop circulator and starting/stopping the 8148 to keep the system loop at the proper (reset) temp.

Mark

R Troughton

Hi Mark,I really

> I don't think you can do what you're

> proposing.

>

> "dry" contacts - a switch "wet"

> contacts - supplies voltage, connect to

> switch

>

> The "burner control" contacts on the

> 8889 are dry. The "thermostat" contacts on the

> 475 are wet. The "boiler aquastat" contacts on

> the 475 are dry.

>

> You don't want to hook wet to

> wet or dry to dry.

>

> Wire up the end switches in

> parallel to the thermostat contacts on the 475,

> the boiler aquastat contacts on the 475 to the

> thermostat contacts on your 8148. Move the circ

> over to the 475.

>

> Mark

R Troughton

Hi Mark,I really appreciate

> I don't think you can do what you're

> proposing.

>

> "dry" contacts - a switch "wet"

> contacts - supplies voltage, connect to

> switch

>

> The "burner control" contacts on the

> 8889 are dry. The "thermostat" contacts on the

> 475 are wet. The "boiler aquastat" contacts on

> the 475 are dry.

>

> You don't want to hook wet to

> wet or dry to dry.

>

> Wire up the end switches in

> parallel to the thermostat contacts on the 475,

> the boiler aquastat contacts on the 475 to the

> thermostat contacts on your 8148. Move the circ

> over to the 475.

>

> Mark

R Troughton

Hi Mark,I really appreciate your

> I don't think you can do what you're

> proposing.

>

> "dry" contacts - a switch "wet"

> contacts - supplies voltage, connect to

> switch

>

> The "burner control" contacts on the

> 8889 are dry. The "thermostat" contacts on the

> 475 are wet. The "boiler aquastat" contacts on

> the 475 are dry.

>

> You don't want to hook wet to

> wet or dry to dry.

>

> Wire up the end switches in

> parallel to the thermostat contacts on the 475,

> the boiler aquastat contacts on the 475 to the

> thermostat contacts on your 8148. Move the circ

> over to the 475.

>

> Mark

R Troughton

Hi Mark,I really appreciate your walking me

> I don't think you can do what you're

> proposing.

>

> "dry" contacts - a switch "wet"

> contacts - supplies voltage, connect to

> switch

>

> The "burner control" contacts on the

> 8889 are dry. The "thermostat" contacts on the

> 475 are wet. The "boiler aquastat" contacts on

> the 475 are dry.

>

> You don't want to hook wet to

> wet or dry to dry.

>

> Wire up the end switches in

> parallel to the thermostat contacts on the 475,

> the boiler aquastat contacts on the 475 to the

> thermostat contacts on your 8148. Move the circ

> over to the 475.

>

> Mark

R Troughton

Hi Mark,

I really appreciate you walking me through this.

I see what you are saying and it makes sense with one exception, if the boiler contacts are dry on the 475 how do they energize the gas valve? I thought you had to have 24v (On low voltage valves) to the valve to trigger it. Or is the 475 not meant to be directly connected to the gas valve?

As far as the wiring itself that looks very straight forward and I'll do it they way you outlined.

Thanks again, hopefully I am not boring you with my questions.

Rob

Mark J Strawcutter

475 boiler contacts

they are actually labeled "boiler aquastat" so no, the 475 is not designed to operate the gas valve directly. The 475 does not provide any high limit safety, which is another reason for still having the 8148 in there.

It's sort of like a cascading "replace the thermostat" scenario. The 8148 has a thermostat connected to it which gets replaced by the 475 which has a thermostat connected to it which gets replaced by the 8889 or zone valve end switches with multiple thermostats.

Mark

Rob T

I noticed

that it was called the Boiler Aquastat and wondered why.

Thanks Mark you have been a great help! I really appreciate your willingness to help and the clarity of your posts..

I will get the 475 and install it this week if I can find the time.

So my system will be setup as follows:

Multiple thermostats (WR 1F80-261 programmable) each to an individual Honeywell zone valve with a single MARS 24v/40va transformer suppling them. (Is this enough for 4 zone valves and thermostats?)

The end switches from the zone valves (Currently in parallel to the 8148e)in parallel to the thermostat in on the 475.

The 475 boiler aquastat out to the thermostat in on the 8148e. The circ pump terminals on the 475 out to the pump.

The boiler contacts on the 8148e out to the boiler, through an MM GuardDog LWCO.

Does this appear to be correct?

Thanks again, from the way nat gas prices are looking I am going to need all the cost cutting help I can get.

Rob

Mark J Strawcutter

transformer and zone valves

Check the VA rating of the zone valves and add 'em up.

Do your thermostats even draw any current? Some run on batteries and draw no current from the system. Others run off system current and use the batteries for backup.

Mark