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Does Anyone Know Anything About Trench Heaters?

Postby Tom_Tom_1st » Wed Apr 01, 2015 6:59 pm

Recently we've bought a house. Quite old one but we decided to change everything inside it. This concerns heating installation as well. My question is: have you heard about trench heaters? Is there anyone who has it and can tell me more whether it's worth installing?
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Postby ericmark » Fri Apr 10, 2015 6:15 am

I have not worked with trench heaters but have worked with Myson heaters which similar to the trench heater uses a small unit to deliver a lot of heat.

With my old central heating system the Myson worked well. It was far smaller than any standard radiator delivering the same heat output. To ensure no exposed part exceeds the permitted temperature for a floor 29 degrees C is considered as the maximum temperature they often need a fan of some type.

It is often the fan which controls room temperature rather than if water flows or not as really you don't want any cold air fanned around. So the standard system is to likely with old building to connect the system in series not parallel every radiator is hot how much heat is extracted depends on the fan speed.

However with modern boilers we use a condensating system to extract the latent heat of evaporation out of the fuel. For this to work the returning water has to be cool and the flame hight is regulated to ensure the returning water is cool enough. When it can get the returning water cool enough it turns off the boiler. This system does not integrate well with controlling fans it needs the water flow to be controlled.

There is no reason why a trench heater should not be designed to work with a standard boiler but to do so it needs far more controls than a standard radiator and as a result the price tends to rocket.

At the moment my Myson is a major stumbling block to fitting a new boiler. The design as it stands does not restrict water flow and once water is hot the Myson fan can run. It has it's own thermostat which when required will switch on the fan and also there is a control to vary the speed of the fan. To work with a condensating boiler it will need a water valve to control the flow rate of the water to match both fan speed and if thermostat is calling for heat. This would mean a major redesign.

It would seem it is permitted to use the latent heat of evaporation to run sterling engines and generate electric which can be like solar panels pumped back into the grid. But at the moment there are very few units made.

The other problem is finding anyone to maintain the system. It is a specialised system and one finds that people trained to work with it demand and get higher wages than the normal heating and ventilating guy.

In the main the problem is a building needs designing to match the heating or vice versa and if starting with a clean sheet integrating heat recovery and heating we can produce a great system which is cheap to run and gives the room an even heat. Using hot air taking the excess heat at top of house and bringing back to bottom of the house is something we expect to see in grand designs. This movement of air through the house means rooms are not individually controlled but the house is centrally controlled allowing units like Hive to adjust whole house from the phone. It would seem hot air heating is common in the USA.

But our heating has taken another track although the boiler is central to the heating system each room is individually controlled. The thermostatic radiator valve has moved on with replacement heads allowing bedrooms only to be heated at night and living rooms only heated in the day with a variation of temperature so in the evening the room is warmer than in the day. Every room can be different.

This simply does not work when you fan hot air around the house. My house is open plan it is today a real pain. It was designed to be heated by a single gas fire in the main room. For me to use a Hive would make sense except I don't have a phone able to control one. But my mother and daughters and sons houses have doors on every room and every room is different.

So it's not the idea of the trench heater that's OK it's how this would fit in with your house. Any of the special heating methods have houses where they work well and houses where they fail. Look at underfloor heating and it's like Marmite either people love it or hate it and when you question them it seems to come down to type of house it is fitted into.

The trench heaters have one huge advantage over other types of underfloor heating. Speed. The fan assisted radiator heats up quick and cools down quick this means the control has to be better or as I found to my cost one feels the room is too cold before it fires up but also too warm before it closes down using a standard thermostat I had to get electronic thermostat with a much smaller gap between on and off temperature.
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Postby Tom_Tom_1st » Mon Apr 13, 2015 6:00 pm

What an exhaustive explanation. Thank you.
I don't think I will turn to something like Myson's. Their radiators seem to be of smaller units and I'm not sure if they'd be enough in our living room for instance. We have something like glass wall there so I thought I would be useful to install a trench heater there to stop cool air flowing to the room... I'm aware that they are to be installed with the joists, so first floor will be ok. I will have to check the ground floor. I know one producent - Verano, they seem to be ok, but you may be right about the guys who would take care about it later...
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Postby Tango&Cat » Thu Apr 30, 2015 6:32 pm

Myson is for kitchen rather. Verano has heaters that look better in other rooms (still don't look like standard radiators) If I were to choose I would take the second. Tey are simply better
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