Underfloor Heating, how should they be filled? Biocide?

[revelation]

 

I have had UFH fitted in around 6 months ago and the system was filled with water and left because of issues with other materials and with trades. 

 

I was wondering if all the water should be drained and re-filled, first as it has been sitting there for 6 months?  Should any chemicals be added into the water such as a biocide of some sort?

 

Any other tips or things to keep in mind?

 

Thanks in advance.

 

 

[JohnMo]

Did you add anti freeze?

 

Either way not sure there will be an issue.  Tap water is treated with chlorine, so any bugs would be killed.

 

Once you get ready to commission you will be flushing to get rid of air, so water will be replaced anyway.

 

If your UFH water goes through a boiler of any sort you should use the manufacturers recommended chemical treatment.

[jfb]

If you are using an ASHP you will definitely want to add anti freeze - if you have a power cut you could end up wrecking the ASHP if the pipes freeze.

[Temp]

I put Fernox F1 in our oil fired UFH system. I think sludge from corrosion products is less with UFH than rads but still don't want it. 

Edited February 1, 2022 by Temp

[Nickfromwales]

6 hours ago, JohnMo said:

Once you get ready to commission you will be flushing to get rid of air, so water will be replaced anyway.

+1. 

[revelation]

I guess from what I have heard in the past is that the system runs at low temperatures compared to rads therefore not everything is killed off, hence the possibility of biocide.

 

So from what I am hearing here is, put some antifreeze in (any particular brand?) and no need for any biocide or any inhibitor?

 

 

[Nickfromwales]

5 hours ago, revelation said:

I guess from what I have heard in the past is that the system runs at low temperatures compared to rads therefore not everything is killed off, hence the possibility of biocide.

 

So from what I am hearing here is, put some antifreeze in (any particular brand?) and no need for any biocide or any inhibitor?

 

 

Is the slab exposed atm? Are you using an ASHP? 
Either way, you really do not want to waste the funds and treat with ( expensive ) treatments until the point it’s purged and filled for the last time. 

[revelation]

The property isn't exposed to the elements and the pipes are in 50mm of the screed.  We are ready for the final fill now so want to be sure to get it right.

 

 

[PeterW]

On 02/02/2022 at 01:36, revelation said:

So from what I am hearing here is, put some antifreeze in (any particular brand?) and no need for any biocide or any inhibitor?

Sorry is this now a fully ready to commission ASHP / UFH system ..?? If so - and if there is no hydraulic separation between ASHP and UFH - then you need a mix of inhibitor and antifreeze. Inhibitor is there to stop galvanic corrosion as pumps; tanks and heat exchangers have different metals in them. 
 

 

[revelation]

On 04/02/2022 at 07:53, PeterW said:

Sorry is this now a fully ready to commission ASHP / UFH system ..?? If so - and if there is no hydraulic separation between ASHP and UFH - then you need a mix of inhibitor and antifreeze. Inhibitor is there to stop galvanic corrosion as pumps; tanks and heat exchangers have different metals in them. 
 

 

 

This is UFH with a systems boiler, no ASHP.

[Nickfromwales]

7 hours ago, revelation said:

 

This is UFH with a systems boiler, no ASHP.

In that case just purge with cold mains after the manifold is fitted, as per the normal commissioning requirements, and treat with inhibitor via the magnetic filter when it has all had a 48hs leak test.

The only time biocides are ever used is in GSHP slinky’s when they’ve been down for some time, and that is to stop the decay of the glycol from any possible contaminates that have ‘taken up residence’. 
Relax, you’re fine with a cold mains flush