Temperature control

[johno12345]

Hi,

I am having problems with a package heat pump system. It is in an office and the occupants are complaining of poor temperature control, basically, its either too hot or too cold, and the temperature changes dramatically throughout the day.

Every time I visit the office, the temperature is either fine, or the controls have been altered.

The unit is a Lennox and was installed in 1995ish. The controller is a DSL700LX. The air conditioning service guys said that its been installed well, with good ductwork and they also think the controller works fine.

I did ask for a price to change the controller to something more modern, but was told that the unit should only be used with the DSL700LX and they quoted £600 to replace it.

One last thing, there is a dip switch to change it between single stage and multi stage, what position should this be in?

We did have the controls locked with the lock switch, and during that time, they still complained about the massive temperature swings.

I'm a bit stuck as to what to do next, I'm not an engineer, just the one that gets all the hassle!


Thanks in advance

[frank]

Before you do anything I would put a temperature and humidity logger in there for a week, just so that you could be sure that it is the system at fault and not the staff moaning.

I've got customers with close control VRV systems installed and the staff still moan.......

What part of the UK are you in?

[johno12345]

not too far from you as it goes, about 60 miles up the m1 at a guess. I do need to speak to more air conditioning companies, but i wonder if the industrial nature of the site puts people off, then when i ask for risk assessments, insurance etc, it sents them running. I have got about 27 units on site, most are mitsi heavy industries with a 0 breakdown record then the old lennox, carrier, IMI units that are a little less reliable

Ill have a look for a remperature logger, not sure where to site it so it cant be tampered with though

[al]

Buy a couple of cheap ones, put them at the ceiling outlets and at head height on pillars/walls.

It could be something as simple as a badly positioned air temperature sensor.

as regards assessments etc all part of doing business now.

al

[Tesla]

Hi Johno
Best to get a couple of data loggers. Put one next to the temperature sensor on the wall and one by the return air. You could use them for any other temp complaints you might get in the future. Check the basics - is the filter and coils clean?
$250 for the controller here http://www.cozyparts.com/Lennox-Part...roductid=13K98 But really is it worth it on a unit this old?
I think if the existing contractor can't fix it get another contractor to do a maintenance and give advice on problem along with a quote for a new unit.
Some times on a low budget contracts or simple smaller systems the juniors are sent out to do maintenance and services - you could speak to the company and ask for a well experienced technician to check the system.

[johno12345]

Buy a couple of cheap ones, put them at the ceiling outlets and at head height on pillars/walls.

It could be something as simple as a badly positioned air temperature sensor.

as regards assessments etc all part of doing business now.

al

exactly what i think too, but its like pulling teeth sometimes!

Hi Johno
Best to get a couple of data loggers. Put one next to the temperature sensor on the wall and one by the return air. You could use them for any other temp complaints you might get in the future. Check the basics - is the filter and coils clean?
$250 for the controller here http://www.cozyparts.com/Lennox-Part...roductid=13K98 But really is it worth it on a unit this old?
I think if the existing contractor can't fix it get another contractor to do a maintenance and give advice on problem along with a quote for a new unit.
Some times on a low budget contracts or simple smaller systems the juniors are sent out to do maintenance and services - you could speak to the company and ask for a well experienced technician to check the system.

coils all clean, filter replaced, then replaced again. its one of those filters thats like white candy floss.

£250 doesnt seem a lot, when it would be several thousand to replace the entire system.

I dont think the stat is in the best place, but it has been fine until recently, just to add to the doubt.


I have a budget to install air conditioning this year, but there are other areas with no air con that seem more deserving than this.

does anyone know any decent companies in south yorkshire?

[frank]

exactly what i think too, but its like pulling teeth sometimes!




coils all clean, filter replaced, then replaced again. its one of those filters thats like white candy floss.

£250 doesnt seem a lot, when it would be several thousand to replace the entire system.

I dont think the stat is in the best place, but it has been fine until recently, just to add to the doubt.


I have a budget to install air conditioning this year, but there are other areas with no air con that seem more deserving than this.

does anyone know any decent companies in south yorkshire?

Not allowed to advertise on here...but send me a PM

[install monkey]

http://www.mediafire.com/view/?ggl5b4f4tncxxb9 page 49 is info on the controller- use the dipswitch for 2 stage cooling- diff is 1 deg preset- there is an option for remote sensing, check sensor resistance- check if the controller is mounted on a internal pillar the coldness of the internal steel work isn't affecting the operation( ensure the cabling is air tight as it penetrates the plasterboard- keep the fans running whilst occupied, check the fresh air damper isn't jammed-draggin in fresh air- reduce the minimum position to 10% open- maybe increase the unoccupied temp setpoint or bring the kit on an hour earlier -good luck

[johno12345]

http://www.mediafire.com/view/?ggl5b4f4tncxxb9 page 49 is info on the controller- use the dipswitch for 2 stage cooling- diff is 1 deg preset- there is an option for remote sensing, check sensor resistance- check if the controller is mounted on a internal pillar the coldness of the internal steel work isn't affecting the operation( ensure the cabling is air tight as it penetrates the plasterboard- keep the fans running whilst occupied, check the fresh air damper isn't jammed-draggin in fresh air- reduce the minimum position to 10% open- maybe increase the unoccupied temp setpoint or bring the kit on an hour earlier -good luck

Its not that advanced a system, the fresh air doesnt have a damper on it, its a 4" duct connected just before the evaporator.

I have checked the controller, and the thermistor was not in the position that it should be, so I have adjusted that. The cable is tight and it seems fine in those regards.

The system failed last night, no cooling or heating, just fan, so the maintenance company came out and it was tripping on high pressure.

The condensor coils have now been degreased and washed and the pressure is now ok. I think the room now feels less humid and stuffy than it did before it tripped out.

So, now I am wondering whether the dirty condensor coil has been causing the problems all along, but with the amount of engineer visits this unit has had, I would really hope not!