Pipe Frost Stat

[scamp]

Our house has a raised floor which gradients from about 4ft-2ft should we fit a pipe frost stat to the central heating pipes?( they are well lagged). If so where is it best installed, under the floor or next to boiler in bathroom?

 

[kevplumb]

if you need a frost stat its no good next to the boiler unless the boiler is in the coldest place
if the pipewowk is lagged i dont see any problem usually fit them to protect boiler in garage or loft etc
if you want to fit one put it where you think its going to be coldest

 

[Kristoflampie]

The siting of a frost stat depends on what it is you want to protect, where water sits static for any length of time it can be vulnerable so lofts and underfloors are old favourites for bursts. Site it where it will get coldest first this will switch the heating or pumps on earlier, moving water will not freeze easily. Lofts are usually far better insulated than underfloors and heat rises so as long as your pipework and tanks are well insulated there I would put your stat in the cellar , mine is in the loft as the eaves let in quite a draught and I have stone floors!!
Some modern boilers are fitted with frost protection already but check what it brings on as it is usually only the pump to move the water.
Hope this helps

 

[ChrisR]

One solution to the "where..." problem is to use TWO frost thermostats. One senses the air temp - nothing aint gonna freeze if the air temp is above zero , (unless there's wind chill, which can be dramatic). Thenput a pipe stat on the return to the boiler set to say 15º (5º would do but 15 is not warm).

Connect them in series such that the boiler comes on if the air temp is below say 3 and the pipes are below say the 15. Then when it gets chilly, the boiler comes on occasionally and all the pipes stay well safe.
Honeywell do a pipe stat which comes in 3 flavors - you need the low limit one.

 

[scamp]

I have just purchased a Honeywell Frost stat and a low limit pipe stat.
They recommend to wire in series.
Thanks.

 

[philhunter]

Thanks ChrisR... this arrangement of frost stat and pipe stat fworks fine

Air stat set to about 5 degrees (mounted outside in IP65 plastic box facing north) and pipestat on return pipe to 15 degrees, for a boiler house ten metres from the house works well... but how much lower could you set them and still be safe from freezing pipes??