Keeping old boiler and adding new pump

camills

Hi guys,

We have an old iron cast boiler that works fine in our house. We would like to better the heating we are getting off the radiators and figured that we would keep the old boiler but change the old radiators to new convector radiators. We were also advised to swap the old pump to a new Alpha 15-60 pump.

Initially we were considering replacing the old boiler to a combi but then decided that the boiler itself seems fine and also heard great things about "old iron cast" boilers as there is very little that could go wrong with it.

I would love to hear your thoughts on this.

We were quoted £990 + VAT to supply & install a new Alpha 15-60 pump and 4 double panel single convector radiators with TRV valves respectively.

Any comments appreciated.

Thanks in advance.

GlynD

Certainly cast iron boilers are excellent quality and last a lifetime. What state is the burner in on the boiler however? I'd be a bit more concerned about that than I would be about the CH pump or rads.

keystone

Unfortunately for you its probably not that far off the mark. Make sure he checks there isn't a magnetite blockage building up in the usual place too.

Cheers

camills

GlynD wrote: »

Certainly cast iron boilers are excellent quality and last a lifetime. What state is the burner in on the boiler however? I'd be a bit more concerned about that than I would be about the CH pump or rads.

Hi GLyn, is checking the burner something that I can do myself or should I give them a nudge when they are doing the job?

keystone

camills wrote: »

Hi GLyn, is checking the burner something that I can do myself?

Nooooooooooooooooo!!

camills

Hahahaha - good thing I waited for your reply!!
Thanks

camills

Hi guys,

So I am very confused now.... so maybe someone can help please :-)

We have the old cast boilers and old double panel radiators (not convectors).

Although we never had any problems with our old boiler, we would like to have the house warmer. So, we had a few people come and check our system and one of them told us there was no need to change the boiler to a combi. Instead, add a new pump to the existing system and change all radiators to new double panel convectors. They said we would notice a massive improvement.

The other guys who came round told us there was no need to replace the old radiators but definitely change the system to a combi!

So now my question is how can I know what to do? We were happy with the thought of no having to change the old boiler as that would save us quite a lot of cash. But now I am wondering whether I will be wasting 1k by changing the radiators and pump when the lack of heat might be from the fact we still have an old system....

Please, let me hear your thought.....

Thank you in advance.

southcoastrgi

If your rads don't have fins ie convector rads then changing to a convector will double the heat output of that rad, so you could keep them as the same size (singles or doubles) or make them smaller, so in laymans terms & for example 600mm high x 600mm long panel rad maybe 1000 btu's (0.30 kw), convector rad same size 2000 btu's (0.60 (figures are just for illustration purposes).

Your orginal boiler would have been sized for the heat output of either the rads (or it should have been for the house heat loss) plus 6000 btu's for the cylinder plus 10%, now by changing the rads the boiler output may or may not be enough for the new rads it really depends on how it was sized in the first place

Have a google at whole house heat calcs put your info in & this should tell you the heat loss & boiler output regd then compare it with your existing boiler

You may need some pipework alterations if you change the rads as yours are prob imperial & new ones are sized in 100mm ie 600, 700, 800 etc (apart from 1300 I dont know anyone that does a 1300)

camills

southcoastrgi wrote: »

If your rads don't have fins ie convector rads then changing to a convector will double the heat output of that rad, so you could keep them as the same size (singles or doubles) or make them smaller, so in laymans terms & for example 600mm high x 600mm long panel rad maybe 1000 btu's (0.30 kw), convector rad same size 2000 btu's (0.60 (figures are just for illustration purposes).

Your orginal boiler would have been sized for the heat output of either the rads (or it should have been for the house heat loss) plus 6000 btu's for the cylinder plus 10%, now by changing the rads the boiler output may or may not be enough for the new rads it really depends on how it was sized in the first place

Have a google at whole house heat calcs put your info in & this should tell you the heat loss & boiler output regd then compare it with your existing boiler

You may need some pipework alterations if you change the rads as yours are prob imperial & new ones are sized in 100mm ie 600, 700, 800 etc (apart from 1300 I dont know anyone that does a 1300)

Thank you so much for your information, it was very helpful.

One other question if I may, could it be that they are suggesting to install the new radiators with a new pump so that this increases the efficiency of the boiler and saves having to upgrade it in order to get the full heat from the new radiators?

Thanks for your time.

Slowly_does_it..

Hi,

Couple of quick questions.
Your current radiators, are they getting warm / hot evenly? (cold across the top = air in the system, cold across the bottom = collection of rust across the bottom)

Is water circulating enough? - water might be really hot when it leaves your boiler, but because the system is blocked up with rust, the boiler turns off / down so it does not boil the water in the boiler, and the heat struggles to make it to the rads.

My vote would be to check the system for blockages - old filters that need cleaning, valves stuck closed or near closed, etc. If this still fails maybe a powerflush, or adding cleaning products to the system, waiting the required week or however long, then flushing the system.

When the system is flowing nicely, and the boiler is proven to be running correctly, then look into further options, like if the old radiators are hot, but the room is still cold, then you will probably need new rads. If the rads are not hot, you will either need a bigger boiler, or a bigger pump if the water leaving the boiler is hot, but the rads are not.

southcoastrgi

A new pump may or may not make a difference, they are suggesting a 15/60 pump which is a 6m head (which is what I'd fit on 98% of jobs), what is your existing pump & please don't say a red or blue one, it maybe too small for the amount of rads or it might be on it's last legs or as suggested above you may have a build up of sludge, or the existing rads maybe too small or not performing as well as they did

I would suggest the people that are saying change the boiler don't really know how to work out the prob that you have