Myson Velaire 90/110 Boiler Advice

[minny]

I have a Myson Velaire 90/110 non-condensing oil fired boiler in my house and I tend to keep the boiler thermostat at Minimum (which equates to 55 degrees according to the manual) for 18 months of the year as it provides enough of heat for my house. It also has additional controls fitted nearby that seems to delay the firing of the boiler by 5-8 minutes to prevent dry-cycling. I have been told this is detrimental to my boiler as the boiler cools down too much and becomes what is like a condensing boiler. Does this sound right?

 

[WHPES]

Wow, a bit of a blast from the past - long time since I last saw one of them!

It is less efficient to run the boiler at too low a temperature as it works harder trying to reach the required level if there is too little difference between the boiler and demand target.

As far as the integrity of the boiler goes, it's probably 30 years or more old so if its still around now then it's not going anyway.

Must be costing you an absolute fortune in oil. Time to consider a more efficient boiler I would say.

Also I am assuming you have no wall thermostat fitted as you mention keeping it on a low setting. You should at least get the controls upgraded. The amount you will save over the winter will be far more than the cost of the electrician.

 

[minny]

Thank you for the advice. Kind of what I figured. I use about 2800l of oil per year to heat a 2500 sq ft house ( 4 beds). I plan to upgrade the boiler next year. We have TRV only. In the meantime what temperature should I have the boiler set at for efficiency? Also just for own knowledge, does the extra timing device that delays boiler firing make it run too cool between firing causing condensation. It is supposed to be a fuel saving device that has a temperature probe fitted to the boiler return pipe and fires it when it gets too cool.

 

[WHPES]

Wow that is a lot of oil! Don't know anything really about the device you mention. Years ago there were different ideas floating round and devices which came and went. Some of them are round-about ways of trying to tweak things. It doesn't make sense to me as time delays actually consume more energy as you need to use more to bring a cool device back up to temperature than to maintain a device at a steady temperature for the same period.

As for boiler temperature setting (knob on the front) for Autumn I would expect it to be somewhere in the middle, and near the max in very cold weather.

Normally you have a thermostat in the boiler itself which clicks on and off at a set temperature, with a set hysterisis to prevent short cycling (rapid clicking on and off at the target temperature).

You could have a house thermostat fitted now to control the heating as this would be re-used when you upgrade the boiler. They look something like this:

http://www.plumbnation.co.uk/site/honeywell-cmt907-7-day-programmerable-room-thermostat/

You can adjust the temperatures required at different times of the day. You can also get a radio controlled version to negate the need to chase cables into walls.

Look at Oil Boilers. Solar PV. Air Source Heat Pumps & Hot Water Cylinders from Grant UK. as you will find loads of useful info on modern oil boilers and systems. Grant is probably the leading oil boiler manufacturer at the moment.

 

[minny]

Great advice about the radio controlled room thermostat. Was wondering how to get about wiring the thing. We've just had the whole house painted and decorated.

 

[WHPES]

The radio controlled thermostat is a CMT927. The thermostat would have to be wired in to turn the boiler on and off depending on room temp assuming you don't have any form of diverter valve or zone valves on the system. When the boiler is replaced, you would end up with a fully controlled and independent controls to the water and heating, unless of course you opt for a combi boiler system whereby the only thing that would remain would be the heating circuit (unless its a single pipe system).

 

[minny]

Will look it up now. Thank you again.

 

[WHPES]

I'm guessing that your heating only comes on when a pump is triggered by a timeclock. The thermostat would have to trigger the pump instead.

Modern controls are "S Plan" or "Y Plan" systems if you look up on Google.