Boiler pressure dropped after installing tado

vaughanleydon

After installing a tado WiFi reciever Internet bridge and thermostat on my Alpha InTec 28XE combi boiler central heating and hot water were lost after 2 days due to a drop in water pressure. This has never happened since I moved in 2 and a half years ago, so it would seem an unlikely coincidence. I was getting error code E10 (low pressure), and the pressure on the barometer was indeed well below 1 bar. I restored the pressure to a little above 1 bar via the filling loop and the error disappeared and all seems to be working. However, I don't really understand why this should have happened, and I'd like to understand so I don't get other issues like this in the future. The evening before this happened I tried using a programmed heating block in the tado app for the first time, so as to warm the house by 8 am. Not sure if that's relevant, but it didn't work and was the last action by me before the error. Is the tado causing a behaviour by the boiler that would affect water pressure that my previous, older Honeywell RF thermostat would not?

vaughanleydon

Thanks for your responses. I have scheduled a gas safe engineer to service the boiler and also diagnose the issue. Since having re-pressurised the system things appear stable at a little over 1 bar. I will continue monitoring.

wateroakley

Hello @vaughanleydon. There is no obvious reason why the boiler would lose pressure simply from fitting Tado TRVs.

Possible suspects … is there any evidence of leakage from the physical TRVs? Perhaps from the pin? Perhaps a weeping compression fitting on a TRV or a weepy bleed valve?

Penny to a pound … any slight leak will be worse when the pipework/rad gets hot. After installation, 'new' compression fittings will usually take a quarter turn more when the pipework gets hot. We've just tightened one weeping TRV compression fitting (quarter-turn) on a large lounge rad after 13 years good behaviour.

vaughanleydon

Hi, Thanks for your response. I haven't actually fitted smart TRVs, but was considering doing so at some point. The change I've made here is to replace my ageing Honeywell wireless RF thermostat and reciever with a Tado Thermostat and WiFi reciever (with Internet bridge). There's no evidence of any leaks with my existing manual TRVs. It may well be a coincidence, but with this being the first boiler issue I've experienced in 2.5 years since moving in, the Tado seems a likely suspect given I'd installed it 2 days beforehand. I can't think of an obvious explanation either, other than some possible undiagnosed preexisting issue made worse due to differences in the way a smart thermostat regulates boiler activity versus a traditional thermostat. I really don't know enough about boilers one way or the other.

davidlyall

There is no way that fitting a Tado smart thermostat could have caused the low pressure issue!

You need to find the leak. Could be internal to the boiler and coming out of the pressure relief pipe outside the property. I had this on a combi many years ago

wateroakley

Hello. If there is no evidence of leaks, or certainty of the boiler pressure two days earlier, I'd be tempted to suggest it's just a coincidence. Philosophers describe acausal coincidences as 'synchronicity'. I find variants of 'Murphy's Law' more compelling. Best to keep an eye on the boiler pressure for a few days.

policywonk

Agree with @wateroakley and @davidyall.

Three options to consider. Boiler's have an overhead tank (or pressure canister) maintaining pressure inside the CH/HW loops. When boilers fire up the water expands and can drop back into the tank or pressure vessel. However when they go cold, they draw upon water from that same tank. It is possible that the ball valve in the overhead tank is stuck, or that the flow side of that tank (heading to the boiler) is blocked, leaving the boiler in a situation where it is losing access to crucial water in the loop.

The second option is that if some of your pipes run under the floor there are leaks. These have to be checked through a pressure test.

The third option is that the boiler has developed a fault in the heat exchange unit.

Once you are certain it isn't the first option, call out a heating engineer linked to that boiler and get them to pressure test the central heating loops and the boiler's heat exchange unit.