Towel Warmer Controls and Zoning

CapeCod

I have two zones, upstairs and downstairs...each with a bathroom with a towel warmer (sole source of heat in bathrooms).  The towel warmers are acting just like radiators though, so sometimes I get lucky and find a warm towel after my shower and sometimes not.  I have to make some changes to my system soon so this is one thing I would like to address at the same time.  Just looking for some input on how others do it.  I was thinking....tie them together (to double the load and lessen short cycling) and have them come on for a few hours constantly in the morning and a few hours before bedtime.  Additionally,  they could come on during the day or at night as needed to help out with space heating.  Or just make them their own zones?  From my previous posts...short cycling is already and issue and may become more of an issue if I choose to only run the towel warmers.  A buffer tank is likely in my future but that is the subject of another upcoming post.  Again, just wondering if I am thinking about this correctly or if someone has other interesting ways to control towel warmers...

SWEI

off thermostat

We plumb them directly off the main loop, bypassing any room/zone stats or valves.  The manual valve they come with works just fine.  Outdoor reset keeps them from going crazy.

CapeCod

bypassing any room/zone stats

OK, but what triggers the boiler to start circulating hot water thru them?  When either one of the zones gets a call for heat, part of the flow is siphoned off to the towel warmer.  In my situation this would be seem to improve matters somewhat because either zone activating would put hot water thru both towel warmers rather than waiting for a call for heat from the zone that the towel warmer is located in.  But just from watching my boiler perform it seems to me it would result in pulses of hot water because it would come to temperature very quickly and then drop quite a bit before firing again.  Perhaps another reason why the buffer tank would help me.  Sorry if I'm asking stupid questions....I'm not going to be installing this but would like to be able to make sure my requests to the installer are valid.  Appreciate the input.  With my boiler I also have the ability to add a second ODR curve...maybe I could use that to drive just the towel warmers?  If my standard ODR curve drives the towel warmers the temperature could be anywhere from 110 to 180 depending on the season.  180 I believe is not recommended for towel warmers because of potential for burners.  I could set the second ODR curve to a constant value?

SWEI

constant cirulation

We don't turn smart cirs on and off with the boiler, so there is always some flow in the system.

CapeCod

smart circs

OK, by smart circulators I assume you mean some kind of ECM,

variable speed like the Alpha?  I also

assume you are using some kind of buffer tank if you employ a modcon?

SWEI

smart circs

= variable speed ECM circulators.  No buffer tank if the mod/con and the radiation are properly sized -- proportional valves help a lot.

CMadatMe

Put Them

On a 2 loop radiant manifold fedding 3/8" pex. Add another zone (alpha or similar pump) and let it run 24/7. I forget what boiler you have but does it have an 120v output that stays energized until warm weather shut down kicks in?

CapeCod

What kind of boiler

I've got a Triangle Tube PE110...it has the WWSD feature which I think just shuts everything down at a predefined temperature.  I made a diagram of my system today...if anyone wants to comment on potential improvements I'd appreciate it.  I asked in another post about an alpha circulator as I think I will add a buffer tank to help my short cycling.

CMadatMe

Trimax

Is this the Trimax or old MCBA controlled boiler? The Trimax AUX output is always powered 120 until WWSD and you could run a constant circulation pump off that output for the towel warmers.

CapeCod

Trimax

It's a Trimax...I think I got one of the first ones when it came out.

CapeCod

constant circ

Great, I like that idea.  Looking at my diagram would you recommend putting a buffer tank right off the supply and a constant circ downstream of that which would feed existing 2 zones plus 3rd zone add on of both towel warmers?  

CMadatMe

Buffer

I would def do the buffer tank. What are all the emitters?

CapeCod

emitters

They are all Myson panel rads.  I derated the capacities based on lowered AWT and wrote them on the rectangles.  The two vertical rectangles are the towel warmers.

CMadatMe

Why Zoned?

Do they all have TRV's on them? Are they being feed with pex off a radiant manifold?

CapeCod

TRV's

Yes, all fed with 1/2" pex al pex from a manifold.  No TRV's...I asked about TRV's as I was used to that after living in Germany for several years but was steered away from that by the installer who said it easier to just zone it.  The main reason for the two different zones is that the smaller zone is just the upstairs bedroom / master bathroom and since it is only used at night, we keep it a couple degrees lower than downstairs.  I actually have a third zone in the basement as well but I ommited that from the discussion to keep things simple.  I have only used it twice so far in the 3 months that I have been heating with the new system.  It seems unable to raise the temperature in the basement as promised.

SWEI

zones and TRVs

For the record, TRVs cost less and work better than typical zoning setups.



If your basement is full of concrete or CMUs, it would require constant heat to achieve any reasonable temperature.  If it's infrequently occupied and the concrete is uninsulated, you could have a losing battle on your hands.  A radiant ceiling or an appropriately sized fan coil might work.

CapeCod

losing battle

Exactly...I remember asking the installer that exact question..."but, won't all that concrete and earth act as a huge heat sink?"....and him "no, don't worry about it, it's at a constant 50 degrees..."



I just wish I joined this forum a couple years earlier.  I turned the radiator on last month at 5:30 in the morning and the basement was at 59 degrees.  It increased a whopping 3 degrees 4 hours later after running constantly. I promptly shut it off and designed to add insulation next summer as my next project.