Boiler's controls: CH and DHW?

[Miao]

Another naive question regarding my Keston C55 (I got the message about how fragile it is) but I can't find a definitive answer in the documentation or online. I suppose the question is valid for any system boiler.
There are 2 thermostats/potentiometers on the front of the boiler. I thought they were Central Heating and How Water but I read that they could be for radiators vs underfloor heating. Which one is true?
And what temperature should I set them up to in winter? My underfloor heating was hardly working when the temperature was set at 60 on both. The gas engineer put them both to the maximum but didn't explain. Should I put the first one close to the maximum (say 70-75) in winter only, and the second one to 60 all year long?
Thanks

 

[Miao]

sorry to insist but what are the two thermostats on the front of the Keston boiler for? Are they similar and regulating the temperature of 2 different flows of water? Is it typically one for central heating and one for hot water, and how do know which one is for what?

 

[alan333]

Can't answer your question other than CH is central heating and DHW is domestic hot water.

 

[Miao]

I could guess that but there is nothing written on the boiler or in the manual. So I have to assume it is a standard thing to separate the thermostats for CH and DHW, and assume also that CH is for both radiators and UFH.
So I am more looking for confirmation that it is the usual thing. Would also like to know what temperature is considered appropriate for the CH part in a large house, considering the UFH wasn't working when the temperature was set below 60

 

[Dan Robinson]

The boiler accepts 2 control inputs and has a different flow temp accordingly.

 

[catnipsta]

Your Keston C55 is a system boiler which heats your domestic water indirectly (within the cylinder). So, I would think that one thermostat controls your UF-heating and the other for your radiators plus heating your DHW inside the cylinder. The temperature of your DHW would be controlled by the cylinder-stat.

If your UF-heating had performed poorly from the start..question would be whether you have adequate insulation below the pipes.

Usually wet UF-heating system temperature is around 40-50c depending on floor type.

 

[Agile]

You should have asked the boiler engineer to explain it to you when he was there.

What was he doing?

What did he say about the underfloor heating?

Tony

 

[Miao]

Unfortunately he made several mistakes and resigned or was fired by the end. The builder finished the work somehow and didn't leave any instructions. I don't know how to find the plumber and the builder won't respond to my queries

 

[AGAS]

to be honest,in that case , get an rig in to check systems and boiler over,to be on safe side .

 

[Miao]

I have a contract with a large gas company but they say they don't want to know about the UFH. Should I bring another RIG?

 

[HootingOwl]

Tell the large gas company to do one and spend your money on someone who actually wants to help you.
sounds like a muffed up installation crowned off with a bit of builder plumbing. Those knobs could be doing anything.....

 

[Dan Robinson]

Does the contract specially exclude underfloor heating?

This is why we advocate small independent engineers.

 

[hazetimesfive]

thats you out then Dan

 

[Miao]

The experience with the independent engineer/plumber was a bit traumatising: choice of Keston, unfinished and undocumented work (no instructions, brand new pipes not identified), new boiler that needs more pressure every week, dirt in the supposedly sealed system and, worst of all, immersion not working (can't get hot water with electricity). I was hoping a big gas company would provide a more professional support but the fact that they won't cover the UFH is a let down. And because the contract is for boiler and controls only it seems they can't help with immersion. Moreover they sent without much explanation a proposal for installing a Magnabooster and hydroflow for 500 quids. I don't even know why I would need that on a relatively new system.
I also wonder whether they could renege on the insurance if I don't follow their recommendation.

 

[AGAS]

ask friends and family for recommendations for an rgi , just ask him to give a detailed survey of your boiler and systems, by the sound of it, it needs it.