Heating issues

[ianmacd]

Help.

I installed a new hot water and heating piping at the weekend. it used to have a towel rail and rad in the bathroom that was always on and acted as a bypass so the boiler always could maintain its flow rate. Because we are moving the bathroom and the old one will become an office, its not really useful to have the rad always on in there any more so I put it on the heating circuit with the rest of the rads. To compensate, I put in an automatic bypass valve that (should) allow the boiler to maintain its minimum flow rate.

Now comes the problem, When the heating is on, all is fine. When the heating and HW are on, all is still fine. Turn the heating off and the boiler goes into protection mode claiming its overheating (and I believe it). I have no idea what to set the auto bypass valve to as I have no idea what flow rate I need nor what the pump speed is (its built into the boiler an Halstead SBX-30).

Any one got any suggestions?

Ian.

 

[NozSpark]

I guess you have a standard "Heat" boiler and valves

If so is the pump connected to the wiring centre or the boiler,, most "Heat" boilers require the pump to be wired to the boiler so that it has "pump over run"

HTH

 

[ianmacd]

Pump is inside the boiler. It does overrun automatically. Just needs a signal when the valves are open (s-plan).

 

[NozSpark]

I know it's a stupid question,,,

but where in the flow and return have you fitted the bypass??

 

[ianmacd]

About 7m from the boiler where the tank is before the motorised vales on the flow linking back to the return. My current working theory is that its a flow issue still and either the auto bypass valve is not working (I have tried it at both extremes) or is not suitable so am going to get some more 'bits' today to hack into the flow and return and put the towel rail and rad in the bathroom back in as another bypass and will see if that helps. We plan to have the towel rails in the new bathrooms like this anyway so will hack in near where they will be and temp route to the existing bathroom.

Hopefully that will sort it.

 

[Chr!s]

Ian

If your boiler is the condensing type, then you want it to operate at a flow diff of around 15 - 20 degrees , so flow 70 from boiler, and 50 at the return.

If the diff is greater then there's not an adequate flow through the boiler.

 

[NozSpark]

You could just replace the auto bypass with a gate valve,, just cracked open?

 

[VoltzElectrical]

or you could just call a heating engineer.

 

[Lurch]

You could just replace the auto bypass with a gate valve,, just cracked open?

Anything but a gate valve. Piece of copper hammered a bit flat would be better than a gate valve IMO, and about as effective. Top tip there actually, why waste money on gate valves when you might as well just flatten the copper.

 

[ianmacd]

Ended up putting bathroom rads back on the flow/return and all seems well again (and bathroom is toasty again too). Will have to see how it goes. Thanks for all the suggestions.

 

[ianmacd]

OK may know what this is now. While turning off the system this morning on my way out I noticed something that I had not noticed the many times before. They do say you always find things when you are not looking for them.

Since putting the bathroom rad/taowl rail on the flow return the boiler, the HW runs fine but I noticed last night it doesn't actually heat anything and the boiler pump is running (as the tank termo says heat) but not firing (I guess as the return was not significantly different in temperature to the flow).

This morning, however, I glanced at the holes in the floor and noticed that the pipes didn't quite line up as I thought they had and then noticed that the flow form the boiler and the flow to the rads (after the heating valve) were switched. This explains why the cylinder never got hot unless the heating was on and why the auto bypass didnt work either. I feel pretty dumb now and unfortunatly we are away for the weekend so I am not going to get a crack at fixing it until Sunday eve (but since I turned it all off before we left, at least it will be nice and cold by then ).

Thanks for the suggestions but I suspect this may fix it .

 

[Andy™]

or you could just call a heating engineer.

or you could shut up.

 

[jl-heating]

glad you sorted it mate .