I used to have a Honeywell AQ6000 in my previous house and it worked perfectly for the last 8 years, now I want to install another one in my new house and have found that Honeywell no longer market it. Can anyone recommend a similar system, I believe that Danfoss make a BEM5000 but am I right in thinking that there is no 2 stage frost protection built in and no valve and pump exercise in summer? Tom
You can find out about the Danfoss one on
I found this product by a company called DCD which claims to have the features that you are looking for, but I don't know how good it is. Price is £340 exc.
Can someone please explain how pump exercise is supposed to work. My Honeywell CM67 programmable room stat has this as an option. However, the stat doesn't switch the pump directly. It switches the heating circuit such that the boiler gets turned on by the mid-position valve. The boiler controls the pump.
It is therefore not possible to run the pump without the boiler also being turned on. I suppose that boiler could possibly be prevented from firing by turning its own stat right down. Is that what you're supposed to do?
I assume that on a fully pumped system - in cases where the boiler and pump run every day throughout the summer to provide hot water - there's no point in having a pump exercise function anyway?
Some of the more sophisticated controllers drive the pump and valve directly and turn them on and open them and simply supply a demand to the boiler. Then they also take care of overrun because they are measuring the return water temperature to the boiler. It's then pretty easy for the pump and valve to be exercised separately.
I think that that's all you can do. The pump shouldn't need to run for very long so it is not a big deal. I wouldn't have any angst about it.
In that case no, but it is a good idea to exercise the valve. They do otherwise have a habit of sticking and then requiring replacement at the start of the heating season. Having a short hit on the heating will do that.
.andy
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