Any suggestions for stopping my condensate boiler pipes from freezing?

Morning ​@Mucky1957. and a warm welcome to the OVO Forum!

Thanks for your interesting post. I’m not an expert in these things myself, but I’m wondering if a trace heating cable running down the pipe might do the trick. I’ve had a look online and they don’t look too dear to get hold of:

https://www.first-traceheating.co.uk/condensate-trace-heater-kits

We have a condensate boiler in an unheated basement. For the last two winters when we had 4 or 5 days of sub-zero temperatures either the pipe outside or the condensate trap box have frozen causing the excess water to back up into the boiler and the boiler shutting down.

A heat trace unit has been attached to the outside pipe..it is currently showing RED but not showing GREEN and it is currently -3c here.

The outside pipe was lagged last year by the installer and I have lagged it again this year over the first lot of lagging with the reflective sheeting. I have also lagged the pipe leading from the boiler to the trap and lagged the trap itself.

My main concern is the three weeks in January that we will be away from home. ( If I was home I could deal with no heating as soon as it happened ). I have my son coming in every couple of days but I don’t expect him to be able to sort out a frozen pipe.

I accept that if it is -3 and the heating has come on then there ‘probably’ isn’t a problem. I need to have 3 or 4 days of really hard cold to be sure. I had a gas engineer out yesterday and he said that IF there was a freeze incident it would likely be the condensate trap inside the basement..and that’s why I want to add a small amount of heating to the basement IF..and I do say IF..the temperature drops really low in the basement.

It sounds like a thermostatic heater would be helpful here.

I’ve been checking online and have found this website which has a calculator for the size of heater for a certain size of room: https://www.electricpoint.com/heating/electric-heating/how-to-calculate-kw-required-to-heat-a-room.

I’ve got this information from an AI search engine tool if it helps (please note, I can’t say whether this information is correct:

Yes, using a small heater with a thermostat to provide frost protection for a condensate trap is a good idea and a common solution. This setup is designed specifically for unheated or minimally heated spaces like lofts, garages, or airing cupboards. 

Safety and Usage Considerations

 

• Plug directly into the wall: Never use an extension cord or power strip with a space heater, as this can cause overheating and fire risk. The heater must be plugged directly into a wall socket.
• Integrated thermostat is better: For frost protection, it is best to use a heater with an integrated thermostat designed for this purpose (often called "frost watchers" or "thermostatic tubular heaters"). These are specifically designed for low-wattage, continuous use.
• Placement: Ensure the heater is placed safely, at least 1 metre (approx. 3 feet) away from any flammable materials (such as furniture, curtains, or insulation material).
• Specific for frost protection: Ensure the external thermostat plug you choose is rated for use with high-wattage appliances and is specifically designed for frost protection (allowing you to set a low temperature threshold like 3°C or 4°C). However, purpose-built "frost watcher" heaters with integrated thermostats are the safest and most reliable option. 

 

Recommended Heater Size:

For a room that is 10' x 8' (80 sq ft) and 7' high, the primary goal is just to prevent freezing, not to heat the entire room comfortably. A very low-wattage heater is sufficient, especially if it's placed near the area needing protection. 

You can use a dedicated "frost watcher" heater: 

 

• Tubular heaters: These are very low wattage, discreet, and specifically designed for frost protection in small spaces. A 1ft (40W) or 2ft (80W) model would be more than enough to protect a localised area like a condensate trap.
• Small convector/plug-in "frost watcher" heaters: These typically have a wattage around 400W to 500W and feature a built-in thermostat. This will also work effectively and provide slightly more ambient heat for the whole room if needed. 

 

Given your goal of just keeping a specific spot above freezing, a low-wattage tubular heater (40-80W) is the most efficient and suitable choice. It provides targeted, low-level heat and is designed to run safely for long periods in cold conditions

wow..many many thanks for all the information.

I have been looking at the frost watcher heaters and the tubular ones..I just need to buy a ‘thermostat/thermometer’ plug to attach it to the heater as I don’t want it running 24/7.

The heater is just an addition to the lagging already done. I’m concerned that what has happened over the last two winters may well happen again.

You can see what I have done with the external pipe and the condensate trap tray ( in red ). This is what I want to aim the heat at.

​@Mucky1957. looking online the thermostatic plugs are widely available.

I’ve also seen ones that allow you to control the plug from an app on your phone, which might be handy if you’re away from the property.

For example: https://www.warm4less.com/product/accessories-controllers/wireless/smart-wifi-thermostat/

thanks for the suggestions. will certainly look at these.

Thanks for your help ​@Nukecad!