Precision Temp question

[jillie]

We have the Precision Temp Jr. in our Ventana. There's a lever in the compartment that we move from 'summer' to 'winter' positions. My question is: If we turn it to the 'winter' position, can we turn on the propane for hot water without heating the antifreeze in the furnace heater pipes if we don't turn on the furnace? In other words, is the furnace antifreeze separated from the water heater antifreeze unless we turn on the furnace? Is there a valve that would stay closed unless we turn on the furnace? Does any of my question make sense?

[Doc C]

The lever to change from summer to winter mode has nothing to do with heating the water

The heater only has 1 circuit and 1 pump which heats the heater antifreeze for both hot water and coach heat.

In the summer mode the heater antifreeze is prevented from circulation through out the coach. When the precision temp turns on, the pump is activiate but the heater antifreeze only circulates with the confines of the precision temp itself and not throughout the coach + the tank inside the precision temp. The lever turns a valve which prevents the pump from sending the heated antifreeze into the coach. Just place your hands on the top of the out pipings near the top of the coach and the pipe is cold.
In this mode you are only heating about 2 of the 6 gallons of the antifreeze (there is 2 gallon in the tank of the precision temp and about 4 gallons in the piping of the interior of the coach).

In the winter mode the heater antifreeze circulate throught the piping in the coach every time the precision temp turn on, even if the coach is not calling for heat. Place your hand on top of the out pipe when heat is turn off, but the precision temp is heating for hot water purposes, or place your hands on the floor inside the coach where the pipes are running underneath - the floor will be warm. When the thermostat calls for inside heat, then the fans at the radiator turn on blowing hot air out into the coach.


I think this is a dumb design, and certainly cuts down on proprane efficiency. In the winter mode if you only need hot water and no heat, you are then required to keep 6 gallons of the heat's antifreeze hot versus the 2 gallons in the summer mode.

This was not explained to me when I bought this option. If I had knew this, then I would have had save myself from $$$ and stayed with the traditional.

Hope this helps.

[jillie]

That's the info I needed. Thanks!

[dougburi]

They guy who has ALL the answers about Precision Temp is:
Gary Wulfmeyer
Service Manager/PrecisionTemp
513-641-4446 ext. 109
800-934-9690 ext. 109
gwulfmeyer@precisiontemp.com

He is very responsive, timely, knows his stuff, and can communicate clearly. Contact him with questions - it's worth the effort.

[jillie]

Thanks, dougburi. We dropped the MH off at the dealer for service yesterday. I asked the service tech about the PT and he didn't have the answer. It doesn't seem to be such a difficult question and it would behoove them to the have the answer for customers. I'll definitely be letting them know the answer.

Love this group!

[jillie]

Got my answer from Gary from PT. Very precise and clear.
"The TwinTemp Jr. system is a single zone, one pump, hydronic system.
With the summer/winter valve in the winter position it will heat approximately 5.5 gallons in the heating side of the system and circulate the hot fluid throughout the coach. In the summer setting it heats approximately 2.25 gallons of fluid contained in the Twintemp and circulates the fluid only within the Twintemp.
There is no other valve to change fluid flow other than the summer winter valve. Whereas a single zone system is used for both hot water and heat, a two zone system has one zone for heating and the other zone for hot water production. Unfortunately there is no way around heating all the plumbing while in the winter mode when producing hot water short of turning the summer/winter valve to the summer position."

[jswickard]

Jillie, I have a 3433 and the same heating unit. I don't see markings that say summer and winter. This is a right angle valve. Can you define which is the summer position and the winter position?

["007"]

Welcome jswickard to irv2 & Newmar forum.
Check this link and the service manual link near bottom of page.
Will give you pictures of what you ask and internal pictures of heater plus maintenance information.
Enjoy the forums and do post often.

Link has been added to Quick Tips.

[jillie]

Originally Posted by jswickard

Jillie, I have a 3433 and the same heating unit. I don't see markings that say summer and winter. This is a right angle valve. Can you define which is the summer position and the winter position?

Here's how I remember it. In the summer I prefer to be OUTSIDE, so the summer position on the valve points to the OUTSIDE. WINTER = INSIDE.

[newmar10]

I would not jump to the conclusion that this is a dumb design. It may be that te Coach manufactures are being cheap. If they purchase the more expensive model Aka duel zone then this does not happen. I am in the process of ordering an electric valve and it will change from summer to winter oly if the thermostat says it requires heat for the blowers. Otherwise it will heat only the hot water tank.

[Doc C]

Yes, I quess it would be cost saving measure by the coach maker.

I would be interested in your modification with the above electric valve. Sounds likes a good ideal and if the modification is not too expensive, could resolve the issue I have with the current design.

Could you please send me additional details.

Doc C

[newmar10]

when i get it done i will send update. It is not cheap. The valve is about 250.00 for a descent one. Wiring will be fairly simple. We do a lot of dry camping so for me this will be well worth it not to heat the hole sysytem unless heat is reqiured. It will also have a manual over ride in it

[Doc C]

Thanks,

I be waiting to see the modifcations. I have had done modifications:

Running an on-off switch that controls the LP from the heater itself into the front pannel with rest of the gauges.

Modifying the temperature fan probes so that heat from the engine assist can be use (fans are set not to turn on unless the glycol is 190 degrees). The problem was with PT proprane off the engine coolant during the winter in my coach only gets up to 175 degrees. Therefore, the engine while driving down the road would only heat heat the PT glycol to 175, fans would never turn on unless I turned on the proprane from the PT. It kinda of defeats the purpose of having an engine asst. If I turn on PT proprane, the heat exchanger in the PT in that configuration not only heats the PT antifreeze from 175 to 190 degrees, but would being transferring heat to heat via the heat exchanger to the cooler engine antifreeze attempting to raise the 20 some gallons of engine antifreeze by about 15 degrees.

Already spent $800 in modifications.

If your modifications works, it would fix my final quirck with this system.

You can also seen me a PM is you wish.

Thanks

Doc C

[newmar10]

I am not sure what you have done but you can bipass the temp censore for the fan switch so they will come on at any temp.You can also put in a switch to shut of the blower motor so the propane will not start and the fans will come on at a lower temp This works better while driving down the road. . I wired mine with switches under the sink where my water pump switch is. If your pluged in you can use the electric heating element to heat all the glycol but it takes along time totally heat the system and the circ pump runs along time which. My only concern with running that way when your plugged in is you may where out the pump. I do alot of dry camping in the summer so having the on off switch inside i just turn the PT on when i want hot water. It is basically instant hot when your in summer mode. I did all this by myself for little cost. As long as you some electrical knoledge and talk to Gary at PT he can tell you which wires to jump