New circulation pump.

denlaw

Hi
We have a duel system (oil, solid fuel) heating the house, started the fire with back boiler on Saturday evening and noticed after an hr that the rads were not heating up, the water in the tank was very warm, had a look in the attic, it was full of steam.

I changed out the circulation pump as per advice from a plumber, the other was 12 yrs old and I had changed it back then with no problems, done the same today, turned everything back on, rads heated up for about an HR then went cold again, I bled the pump again and noticed there was no water coming out, went back up the attic and it was full of steam again...... anyone have an idea what's wrong before I pull the plug and get a proper plumber in..

The new pump is a dab evosta 2

jimf

is it working ok with the oil

if yes having ruled out the pump are you sure the stat operating the pump is working

or you possibly have a non return valve issue

just to add im not a plumber just little bits i have learned over the years around here

denlaw

jimf wrote: »

is it working ok with the oil

if yes having ruled out the pump are you sure the stat operating the pump is working

or you possibly have a non return valve issue

just to add im not a plumber just little bits i have learned over the years around here

Working fine with the oil, stat is operating, think I could have a non return valve problem , I'll have another look at in the morning.
Thanks..

John.G

Even though probably not the problem, the DAB2 is a very powerful pump (almost 7M) and the traditional "fixed speed" curve 2 is 5.4m which can cause venting, speed 3 is higher again at 6.8M, would suggest changing to (constant pressure) CP mode 2 (3.8M) and see how you get on. (CP3 is 4.8M)

denlaw

John.G wrote: »

Even though probably not the problem, the DAB2 is a very powerful pump (almost 7M) and the traditional "fixed speed" curve 2 is 5.4m which can cause venting, speed 3 is higher again at 6.8M, would suggest changing to (constant pressure) CP mode 2 (3.8M) and see how you get on. (CP3 is 4.8M)

would you recommend that setting for 13 rads in the house?

John.G

Difficult to answer that, it depends on the installation, pipe manifold sizing etc but on CP2 the DAB will maintain a constant 3.8M head up to 25 LPM, CP3 will give up to 17LPM at 4.8M head and then fall gradually to 3.8M between 17LPM and 25LPM.
I have 10 rads and a 3M head gives me all hot rads. What mode/setting is/was the DAB on just now?.

What was the old pump make/model/setting? or/and the OF boiler make/model/setting and that will tell a lot.

denlaw

John.G wrote: »

Difficult to answer that, it depends on the installation, pipe manifold sizing etc but on CP2 the DAB will maintain a constant 3.8M head up to 25 LPM, CP3 will give up to 17LPM at 4.8M head and then fall gradually to 3.8M between 17LPM and 25LPM.
I have 10 rads and a 3M head gives me all hot rads. What mode/setting is/was the DAB on just now?.

What was the old pump make/model/setting? or/and the OF boiler make/model/setting and that will tell a lot.

the old pump was a heat merchant, it was set to the number three setting.

I set the new one to the highest output, guess I blew the non return valve.

John.G

That old heat merchants was possibly a HM 4-7 which was a relabeled Dab Evosta 4-7 with almost exactly the same head/flow as your new pump on full speed. NRVs can take ~ 6 times the head generated by any circ pump so couldn't really damage it, it's possibly stuck or partially blocked with sludge especially if its of the spring loaded type in which sludge can easily build up in the valve guides.

jimf

if its the old europa spring type valve i would be having a good look at it before you go any further

change it for the flap type instead

denlaw

Update on circulation pump.

found the problem, when the old pump failed, i went up into the attic to check if i had water in the expansion tank, i had to rip off the insulation that i had over the tank to take a peek, a little piece of tape had fallen in the tank, it had got stuck in the feed hole which was why the pump wasn't getting any water, pulled the tape out and its been working like a dream since, in fact, its the first time in about 10 yrs that all the rads have been working properly.

Thanks again to all for the input.