fan coil units

[lionplaza]

I was wondering if anyone can help me. I supervise a site that has approx. 750 Fan Coil Units. The heating and chilled coils are fed from 15mm pipe but the coils themselves reduce to maybe 7 or 8mm. Each heating and chilled coil is controlled by an actuator on a 4 port valve.
The problem I have is that when the heating actuators fail (sticking in the open position) the coil overtime eventually blocks. There are flushing points before each coil but on the flow side and don't really help when the coil is totally blocked as not enough pressure is coming through the return to unblock it.
Are there any other methods that would help unblock coils like this? Would a power flush unit be something I should look into buying or would it not be effective in my case?
We have tried disconnecting the coils from the 4 port valve to pump some compressed air through but even this doesn't work most of the time.
Any suggestions would be great.

Cheers.

 

[prs1]

not an expert but what ever u do u need to get rid of the carp out of the system.
some sort of inline filter arrangment ,cleaned reguarly to start.
Is the water quality-and chemical levels monitored and topped up as necessary?
Or have these units been neglected in the past?

 

[lionplaza]

No, all the pseudomonas levels are ok. We have a specialist water company that doses quarterly if required.

We pulled out a 4 port valve earlier today that had quite a build up of crap in it. Replaced it with a new one but it still isn't helping with the coil blockage.

I think I will have to resort to a power flushing unit. I hope they aren't noisy because Tenants will go ape. Cheers.

 

[migoplumber]

you will probably end up flushing each unit seperately. i imagine your on steel pipework ?

 

[Puddle]

I think I will have to resort to a power flushing unit. I hope they aren't noisy because Tenants will go ape. Cheers.

Sounds like you are going to set up a maintenance prevention program,flushing through coils on regular basis

imho

 

[tesla]

Hi
This is my first post on the blog so bear with me. I am an engineer and control a building with many more FCU that you have at present, so I hope thias allows me to offer some advice.

Firstly you have not said what type of pipework you hav, would therfore assume that you have mild steel risers and then possible change to copper at FCU's.

It is all well and good your water treatment company testing for bugs, but yor priorty should be corrosion and inhibition. It sound like you have a system that needs a flush and then corrosion treatment. even though your system is a closed loop, oxygen still gets entrapped, what colour is the water in your system. if it is brown it is Fe, if it is black it is hydrogen sulphide neither much good for flow rates.

If you can come back with some answers I may be able to help.

type of pipework
colour of water
do you do TDS testing
what is the Ph of the water
does it have an antifreeze
do you have inhibitor dosing manual/automatic
how old is the system

regards

Tesla

 

[kingkenny]

do you have a strainer on the flow to FCU on the chilled and heating side?.
is there also flushing points on both.