General plumbing/heating questions!

[95matt]

Hi all,

New to the forums and know little about about all this.

I've recently moved and the new house was built in 1988. It has the original boiler, controls etc.

I have a couple of issues. First of I've tried doing so research, and think I have a vented indirect system.

The first problem is we have the hot water only on in the morning (it's summer?!!) and the system makes quite a racket, it sounds like it's coming from the the pump in the airing cupboard (it's red and black and has grundfos on it). It's a grinding noise. I'm not sure why it's using the pump for hot water as I thought it was a central heating pump?

Looking at the pipes going in to this pump the water feed pipe is first, then the vent feed, then the pump, the water pipe passes under the vent pipe and is joined by what i'd call an inverted T. This sounds as though it can take in air as well as water?

Second problem is looks like we have to have the CH and HW on at the same time (well CH can be off as it is now or both on). Is this just the control unit or something more?

Sorry for going on, I find it best to have an basic idea before getting the trades in to quote for whole new systems.

Thanks in advance, Matt.

 

[Dannypipe]

Your pump sounds knackered. The reason the pump is on is because it pumps the primary (CH) around a short run of coiled pipe in your hotwater cylinder. The hotwater in this coil indirectly heats the water in the cylinder.

You could possibly heat your water with an immersion heater if you have one fitted and it works.

Changing a pump is a straight forward job but due to the fact that your knowledge is so limited, I would suggest you get a competant plumber in to do it. Let the forum know your area, and you may pick one up from here. Good luck.

Oh and you can have just hotwater on from your boiler, but the pump will still run for the reasons I explained at the very start.

 

[95matt]

Ok thanks, so in essence the how water cylinder is just the start of the CH run, and by having the HW on and CH heating off it simply does a short round, I.e. a long round would be HW and rads.

So then at present I can have HW only, HW and CH, but not CH only, so pressumably I need to modify (by I - I mean a plumber) the system so it has a 3rd option of CH only.

There's a lot of air in the system, and 1 rad doesn't heat up so I'll try sorting that out first!

Thanks for your help.

 

[justlead1]

Hi. The modification you suggest may not be required. When installing this type of system. It is assumed that hot water is the number 1 requirements central heating number 2. As in most cases the hot water cylinder has a stat attached which monitors the water temp. Once the temp has been achieved the circulation through the cylinder stops but will continue around heating circuit if called for.

 

[GrahamM]

Hi. The modification you suggest may not be required. When installing this type of system. It is assumed that hot water is the number 1 requirements central heating number 2. As in most cases the hot water cylinder has a stat attached which monitors the water temp. Once the temp has been achieved the circulation through the cylinder stops but will continue around heating circuit if called for.

Just to add to what justlead1 said above.
There is what we call 'Y'-plan or mid-position valve setup. This is not so common now as the main problem is you cannot control the heating of the water independetly. There is always water going to the tank and is controlled by the tank thermostat switching boiler on/off as tank temperature falls/rises. So basically, you can have:

• HW only
• HW & CH
• cannot have CH only

The more controlable 'S'-plan system has 2 independent valves the control HW & CW independently giving you full control. This is the more desireable setup for controlling your system.

It is not usually too difficult to convert a 'Y'-plan to the more controllable 'S'-plan. Giving you independent control. It may involve some extra wireing from the boiler to a new control panel and then to a new valve system on you tank.

Your pump will need be looked at if making grinding noises though, but that should not be too much of a job.

 

[95matt]

Thanks for this.

So what happens when the HW is up to temperature, pressumably there is a bypass of some sort or else we'd only have central heating for the short time the tank heats up?

 

[PlumbBobBob]

yes the three way valve acts as a diverter valve when hot water is satisfied the valve diverts the water through the ch. the valve is called three way because you can have hot water only ch only and hot water and ch.

steve

 

[Toddyplumb]

There are 2 types of 3 port valve , full divertor and Mid position. Both give independant control of heating and hot water. The difference being the mid position will share the flow to both at the same time. The full divertor gives priority to hot water and when satisfied motors to heating
GrahamM have you made a typo

 

[ferret]

There are 2 types of 3 port valve , full divertor and Mid position. Both give independant control of heating and hot water. The difference being the mid position will share the flow to both at the same time. The full divertor gives priority to hot water and when satisfied motors to heating
GrahamM have you made a typo

and also the programmer may be switchable for 16 programmes but at that age i,d guess its a miniminder or similar.

 

[plumbandplumber]

Just to add to what justlead1 said above.
There is what we call 'Y'-plan or mid-position valve setup. This is not so common now as the main problem is you cannot control the heating of the water independetly. There is always water going to the tank and is controlled by the tank thermostat switching boiler on/off as tank temperature falls/rises. So basically, you can have:

• HW only
• HW & CH
• cannot have CH only

The more controlable 'S'-plan system has 2 independent valves the control HW & CW independently giving you full control. This is the more desireable setup for controlling your system.

It is not usually too difficult to convert a 'Y'-plan to the more controllable 'S'-plan. Giving you independent control. It may involve some extra wireing from the boiler to a new control panel and then to a new valve system on you tank.

Your pump will need be looked at if making grinding noises though, but that should not be too much of a job.

I'm afraid this is wrong. Y plan, with a 3 port valve, can give independent control of CH and HW, as good as S Plan. Y Plan has 3 modes 1) CH 2) HW 3) Mid-position, ie. CH&HW.

The question that no one has asked, is what motorised valve does the OP have, 2 port or 3 port. And how many motorised valves.

I have recently converted a system of a similar vintage for a customer, where there was only a 2 port valve controlling the CH, and nothing on the HW. No cylinder stat either. HW could be on on its own, but if you wanted CH, the HW cylinder received heat as well.

It's poss that the OP has this set up. If you have a single 2 port motorised valve, then its usually a case of adding a second one, and poss a programmer change, to give you independent control.

Alternatively, it could just be that the programmer doesn't allow seperate HW and CH timings.